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@@ -64,13 +64,13 @@ stack for the nesting.)
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The call stack still needs room for the levels that are recursed into, and the default limit assumes a stack of ordinary
|
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size. The stack that an operation needs is roughly proportional to the limit; with the default of 128 levels, the most
|
||||
demanding operation (`dump` in an unoptimized build) needed up to 288 KiB, and an optimized build needed 48 KiB or less,
|
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in measurements on macOS with arm64. The most demanding operation needed this much stack at the limits `0`, `32`,
|
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`128`, and `254`:
|
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demanding operations (copying a value and converting it to another `basic_json` type, in an unoptimized build) needed
|
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up to 224 KiB, and an optimized build needed 48 KiB or less, in measurements on macOS with arm64. The most demanding
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operation needed this much stack at the limits `0`, `32`, `128`, and `254`:
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| Stack needed, in KiB | limit 0 | limit 32 | limit 128 (default) | limit 254 |
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|---|---:|---:|---:|---:|
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| unoptimized build (`-O0`) | 16 or less | 80 | 288 | 576 |
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| unoptimized build (`-O0`) | 16 or less | 64 | 224 | 448 |
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| optimized build (`-O2`) | 16 or less | 16 or less | 48 | 112 |
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A thread with a smaller stack (a task of a real-time operating system, a fiber, or a thread of the musl C library, whose
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@@ -81,6 +81,20 @@ result. See the [documentation of the macro](../../api/macros/json_recursion_dep
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the speed, and the rules for choosing a value. Destroying a value (its destructor) recurses over the same number of
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levels and then continues without the call stack, and needs 32 KiB or less at every limit.
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!!! warning "Indented output and flattened keys grow with the depth"
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Some results are larger than the value by a factor of its nesting depth.
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[`dump`](../../api/basic_json/dump.md) with an `indent` of `n` (and likewise `operator<<` with `std::setw(n)` and
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[`basic_json_view::dump`](../../api/basic_json_view/dump.md)) writes up to `n` characters per nesting level in
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front of every line, and [`flatten`](../../api/basic_json/flatten.md) repeats the path of every value in its key.
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For the 80,001-byte array `[1,[1,...[1,1]...]]` with 20,000 levels, `dump(1)` returns 600 MB, `dump(4)` 2.4 GB,
|
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and the keys of `flatten()` hold 400 MB. A compact `dump()` without indentation stays the size of the value. If you
|
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pretty-print, log, or flatten untrusted input, limit its nesting depth while parsing, for example with a
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||||
[parser callback](parser_callbacks.md#recipe-max-nesting-depth-via-a-callback): with a limit of `d`, every line has
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at most `n * d` indentation characters, and every flattened key has at most `d` reference tokens.
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[`JSON_RECURSION_DEPTH_LIMIT`](../../api/macros/json_recursion_depth_limit.md) does not help here: it changes only
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how much of the call stack a walk uses, never its result, and it does not limit the depth that `parse()` accepts.
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## Input size
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The library does not limit the overall size of a JSON text; a value nested or wide enough will use memory
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@@ -140,6 +154,20 @@ values for a repeated key ends up in the parsed object. If your application must
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silently resolving them one way or another, see the
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[parser callback recipe for rejecting duplicate keys](parser_callbacks.md#recipe-rejecting-duplicate-object-keys).
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## Objects with many keys in `ordered_json`
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[`ordered_json`](../../api/ordered_json.md) keeps the members of an object in a vector in insertion order
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([`ordered_map`](../../api/ordered_map.md)) and finds a key by searching all members. Parsing JSON text into an
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`ordered_json` avoids that search for objects with many keys and takes linear time. The binary readers
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([`from_cbor`](../../api/basic_json/from_cbor.md), [`from_msgpack`](../../api/basic_json/from_msgpack.md),
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[`from_ubjson`](../../api/basic_json/from_ubjson.md), [`from_bjdata`](../../api/basic_json/from_bjdata.md),
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[`from_bson`](../../api/basic_json/from_bson.md), and [`from_bon8`](../../api/basic_json/from_bon8.md)) do not yet:
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reading an object of `n` keys into an `ordered_json` costs time proportional to `n²`. A flat object of 40,000 keys
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(about 300 KB of CBOR) takes about 1.3 s, against a few milliseconds as JSON text or into a `json`
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([#6104](https://github.com/nlohmann/json/issues/6104)). `json` is not affected. If you read untrusted binary input
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into `ordered_json`, bound the input size more tightly, read it into a `json`, or reject objects with many keys in a
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[SAX handler](sax_interface.md).
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## Numbers
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A number whose value cannot be represented — for instance `1E1000`, which overflows `double` — is rejected while
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@@ -171,9 +199,11 @@ indices (or the pointer as a whole) before using them, or use [`at`](../../api/b
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- Wrap parsing in a `#!cpp try`/`#!cpp catch` block, or use `allow_exceptions=false`/`accept()` if your environment
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cannot use exceptions; never let `JSON_NOEXCEPTION`'s `abort()` be the first time you think about error handling.
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- If the input's nesting depth matters to you, enforce your own limit with a
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[parser callback](parser_callbacks.md#recipe-max-nesting-depth-via-a-callback) or a
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- If the input's nesting depth matters to you (for example because you pretty-print, log, or flatten it), enforce your
|
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own limit with a [parser callback](parser_callbacks.md#recipe-max-nesting-depth-via-a-callback) or a
|
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[SAX handler](sax_interface.md); the library bounds the call stack but not memory use.
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- If you read untrusted binary input into `ordered_json`, mind that objects with many keys are
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[slow to read](#objects-with-many-keys-in-ordered_json).
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- Bound the size of the input itself before parsing, independent of the library's own bounded allocations for binary
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format lengths.
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- Decide up front how you want a string with invalid UTF-8 — from any source, not only parsing — to be serialized
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@@ -1 +1 @@
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<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=description content="JSON for Modern C++ is a header-only C++11 library that makes JSON a first-class data type."><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/features/parsing/untrusted_input/" rel="canonical"><link href=../sax_interface/ rel=prev><link href=../../assertions/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.8.0"><title>Parsing Untrusted Input - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.57a0d79d.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.fb2fffe2.min.css><link rel=stylesheet href=../../../css/custom.css><link rel=stylesheet href=../../../css/brand.css><link rel=stylesheet href=../../../css/fig-sax.css><link rel=stylesheet href=../../../css/fig-jsonview.css><link rel=stylesheet href=../../../css/fig-exceptions.css><link rel=stylesheet href=../../../css/fig-pointer.css><link rel=stylesheet href=../../../css/fig-charts.css><link rel=stylesheet href=../../../css/fig-integration.css><link rel=stylesheet href=../../../css/fig-macros.css><script>__md_scope=new URL("../../..",location),__md_hash=e=>[...e].reduce(((e,_)=>(e<<5)-e+_.charCodeAt(0)),0),__md_get=(e,_=localStorage,t=__md_scope)=>JSON.parse(_.getItem(t.pathname+"."+e)),__md_set=(e,_,t=localStorage,a=__md_scope)=>{try{t.setItem(a.pathname+"."+e,JSON.stringify(_))}catch(e){}}</script></head> <body dir=ltr data-md-color-scheme=default data-md-color-primary=custom data-md-color-accent=custom> <input class=md-toggle data-md-toggle=drawer type=checkbox id=__drawer autocomplete=off> <input class=md-toggle data-md-toggle=search type=checkbox id=__search autocomplete=off> <label class=md-overlay for=__drawer></label> <div data-md-component=skip> <a href=#parsing-untrusted-input class=md-skip> Skip to content </a> </div> <div data-md-component=announce> </div> <header class=md-header data-md-component=header> <nav class="md-header__inner md-grid" aria-label=Header> <a href=../../.. title="JSON for Modern C++" class="md-header__button md-logo" aria-label="JSON for Modern C++" data-md-component=logo> <img src=../../../images/wordmark-header.svg alt=logo> </a> <label class="md-header__button md-icon" for=__drawer> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg> </label> <div class=md-header__title data-md-component=header-title> <div class=md-header__ellipsis> <div class=md-header__topic> <span class=md-ellipsis> JSON for Modern C++ </span> </div> <div class=md-header__topic data-md-component=header-topic> <span class=md-ellipsis> Parsing Untrusted Input </span> </div> </div> </div> <form class=md-header__option data-md-component=palette> <input class=md-option data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme=default data-md-color-primary=custom data-md-color-accent=custom aria-label="Switch to dark mode" type=radio name=__palette id=__palette_0> <label class="md-header__button md-icon" title="Switch to dark mode" for=__palette_1 hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a4 4 0 0 0-4 4 4 4 0 0 0 4 4 4 4 0 0 0 4-4 4 4 0 0 0-4-4m0 10a6 6 0 0 1-6-6 6 6 0 0 1 6-6 6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12z"/></svg> </label> <input class=md-option data-md-color-media="(prefers-color-scheme: dark)" data-md-color-scheme=slate data-md-color-primary=custom data-md-color-accent=custom aria-label="Switch to light mode" type=radio name=__palette id=__palette_1> <label class="md-header__button md-icon" title="Switch to light mode" for=__palette_0 hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 18c-.89 0-1.74-.2-2.5-.55C11.56 16.5 13 14.42 13 12s-1.44-4.5-3.5-5.45C10.26 6.2 11.11 6 12 6a6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12z"/></svg> </label> </form> <script>var palette=__md_get("__palette");if(palette&&palette.color){if("(prefers-color-scheme)"===palette.color.media){var media=matchMedia("(prefers-color-scheme: light)"),input=document.querySelector(media.matches?"[data-md-color-media='(prefers-color-scheme: light)']":"[data-md-color-media='(prefers-color-scheme: dark)']");palette.color.media=input.getAttribute("data-md-color-media"),palette.color.scheme=input.getAttribute("data-md-color-scheme"),palette.color.primary=input.getAttribute("data-md-color-primary"),palette.color.accent=input.getAttribute("data-md-color-accent")}for(var[key,value]of Object.entries(palette.color))document.body.setAttribute("data-md-color-"+key,value)}</script> <label class="md-header__button md-icon" for=__search> <svg xmlns=http://www.w3.org/2000/svgLine truncated
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<!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=description content="JSON for Modern C++ is a header-only C++11 library that makes JSON a first-class data type."><meta name=author content="Niels Lohmann"><link href="https://json.nlohmann.me/features/parsing/untrusted_input/" rel="canonical"><link href=../sax_interface/ rel=prev><link href=../../assertions/ rel=next><link rel=icon href=../../../assets/images/favicon.png><meta name=generator content="mkdocs-1.6.1, mkdocs-material-9.8.0"><title>Parsing Untrusted Input - JSON for Modern C++</title><link rel=stylesheet href=../../../assets/stylesheets/main.57a0d79d.min.css><link rel=stylesheet href=../../../assets/stylesheets/palette.fb2fffe2.min.css><link rel=stylesheet href=../../../css/custom.css><link rel=stylesheet href=../../../css/brand.css><link rel=stylesheet href=../../../css/fig-sax.css><link rel=stylesheet href=../../../css/fig-jsonview.css><link rel=stylesheet href=../../../css/fig-exceptions.css><link rel=stylesheet href=../../../css/fig-pointer.css><link rel=stylesheet href=../../../css/fig-charts.css><link rel=stylesheet href=../../../css/fig-integration.css><link rel=stylesheet href=../../../css/fig-macros.css><script>__md_scope=new URL("../../..",location),__md_hash=e=>[...e].reduce(((e,_)=>(e<<5)-e+_.charCodeAt(0)),0),__md_get=(e,_=localStorage,t=__md_scope)=>JSON.parse(_.getItem(t.pathname+"."+e)),__md_set=(e,_,t=localStorage,a=__md_scope)=>{try{t.setItem(a.pathname+"."+e,JSON.stringify(_))}catch(e){}}</script></head> <body dir=ltr data-md-color-scheme=default data-md-color-primary=custom data-md-color-accent=custom> <input class=md-toggle data-md-toggle=drawer type=checkbox id=__drawer autocomplete=off> <input class=md-toggle data-md-toggle=search type=checkbox id=__search autocomplete=off> <label class=md-overlay for=__drawer></label> <div data-md-component=skip> <a href=#parsing-untrusted-input class=md-skip> Skip to content </a> </div> <div data-md-component=announce> </div> <header class=md-header data-md-component=header> <nav class="md-header__inner md-grid" aria-label=Header> <a href=../../.. title="JSON for Modern C++" class="md-header__button md-logo" aria-label="JSON for Modern C++" data-md-component=logo> <img src=../../../images/wordmark-header.svg alt=logo> </a> <label class="md-header__button md-icon" for=__drawer> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M3 6h18v2H3zm0 5h18v2H3zm0 5h18v2H3z"/></svg> </label> <div class=md-header__title data-md-component=header-title> <div class=md-header__ellipsis> <div class=md-header__topic> <span class=md-ellipsis> JSON for Modern C++ </span> </div> <div class=md-header__topic data-md-component=header-topic> <span class=md-ellipsis> Parsing Untrusted Input </span> </div> </div> </div> <form class=md-header__option data-md-component=palette> <input class=md-option data-md-color-media="(prefers-color-scheme: light)" data-md-color-scheme=default data-md-color-primary=custom data-md-color-accent=custom aria-label="Switch to dark mode" type=radio name=__palette id=__palette_0> <label class="md-header__button md-icon" title="Switch to dark mode" for=__palette_1 hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 8a4 4 0 0 0-4 4 4 4 0 0 0 4 4 4 4 0 0 0 4-4 4 4 0 0 0-4-4m0 10a6 6 0 0 1-6-6 6 6 0 0 1 6-6 6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12z"/></svg> </label> <input class=md-option data-md-color-media="(prefers-color-scheme: dark)" data-md-color-scheme=slate data-md-color-primary=custom data-md-color-accent=custom aria-label="Switch to light mode" type=radio name=__palette id=__palette_1> <label class="md-header__button md-icon" title="Switch to light mode" for=__palette_0 hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M12 18c-.89 0-1.74-.2-2.5-.55C11.56 16.5 13 14.42 13 12s-1.44-4.5-3.5-5.45C10.26 6.2 11.11 6 12 6a6 6 0 0 1 6 6 6 6 0 0 1-6 6m8-9.31V4h-4.69L12 .69 8.69 4H4v4.69L.69 12 4 15.31V20h4.69L12 23.31 15.31 20H20v-4.69L23.31 12z"/></svg> </label> </form> <script>var palette=__md_get("__palette");if(palette&&palette.color){if("(prefers-color-scheme)"===palette.color.media){var media=matchMedia("(prefers-color-scheme: light)"),input=document.querySelector(media.matches?"[data-md-color-media='(prefers-color-scheme: light)']":"[data-md-color-media='(prefers-color-scheme: dark)']");palette.color.media=input.getAttribute("data-md-color-media"),palette.color.scheme=input.getAttribute("data-md-color-scheme"),palette.color.primary=input.getAttribute("data-md-color-primary"),palette.color.accent=input.getAttribute("data-md-color-accent")}for(var[key,value]of Object.entries(palette.color))document.body.setAttribute("data-md-color-"+key,value)}</script> <label class="md-header__button md-icon" for=__search> <svg xmlns=http://www.w3.org/2000/svgLine truncated
|
||||
@@ -24,15 +24,19 @@ Neither the parser nor the binary readers impose a limit on how deep the input m
|
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|
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Once a value has been parsed, operations that walk it recursively — serializing it with [`dump`](https://json.nlohmann.me/api/basic_json/dump/index.md), hashing it, copying it, comparing two values with `==`, `<`, or (in C++20) `<=>`, merging with [`update`](https://json.nlohmann.me/api/basic_json/update/index.md), applying a [`merge_patch`](https://json.nlohmann.me/api/basic_json/merge_patch/index.md), creating a patch with [`diff`](https://json.nlohmann.me/api/basic_json/diff/index.md) or [`merge_diff`](https://json.nlohmann.me/api/basic_json/merge_diff/index.md), converting it to another `basic_json` type, destroying it, and the binary writers (`to_cbor`, `to_msgpack`, ...) — descend at most [`JSON_RECURSION_DEPTH_LIMIT`](https://json.nlohmann.me/api/macros/json_recursion_depth_limit/index.md) levels on the call stack, 128 by default, and continue below that with an explicit stack on the heap. So the call stack does not grow with the nesting depth of the value, however deeply it is nested. ([`flatten`](https://json.nlohmann.me/api/basic_json/flatten/index.md), [`unflatten`](https://json.nlohmann.me/api/basic_json/unflatten/index.md), and [`to_bson`](https://json.nlohmann.me/api/basic_json/to_bson/index.md) never use the call stack for the nesting.)
|
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|
||||
The call stack still needs room for the levels that are recursed into, and the default limit assumes a stack of ordinary size. The stack that an operation needs is roughly proportional to the limit; with the default of 128 levels, the most demanding operation (`dump` in an unoptimized build) needed up to 288 KiB, and an optimized build needed 48 KiB or less, in measurements on macOS with arm64. The most demanding operation needed this much stack at the limits `0`, `32`, `128`, and `254`:
|
||||
The call stack still needs room for the levels that are recursed into, and the default limit assumes a stack of ordinary size. The stack that an operation needs is roughly proportional to the limit; with the default of 128 levels, the most demanding operations (copying a value and converting it to another `basic_json` type, in an unoptimized build) needed up to 224 KiB, and an optimized build needed 48 KiB or less, in measurements on macOS with arm64. The most demanding operation needed this much stack at the limits `0`, `32`, `128`, and `254`:
|
||||
|
||||
| Stack needed, in KiB | limit 0 | limit 32 | limit 128 (default) | limit 254 |
|
||||
| ------------------------- | ---------- | ---------- | ------------------- | --------- |
|
||||
| unoptimized build (`-O0`) | 16 or less | 80 | 288 | 576 |
|
||||
| unoptimized build (`-O0`) | 16 or less | 64 | 224 | 448 |
|
||||
| optimized build (`-O2`) | 16 or less | 16 or less | 48 | 112 |
|
||||
|
||||
A thread with a smaller stack (a task of a real-time operating system, a fiber, or a thread of the musl C library, whose default stack is 128 KiB) can still overflow its stack on deeply nested input, which is why the limit can be lowered: define `JSON_RECURSION_DEPTH_LIMIT` to a smaller value, down to `0`, before including the library. Such a limit changes only the stack that is needed and the speed (values nested more deeply than the limit are walked more slowly), never a result. See the [documentation of the macro](https://json.nlohmann.me/api/macros/json_recursion_depth_limit/index.md) for the complete tables, the speed, and the rules for choosing a value. Destroying a value (its destructor) recurses over the same number of levels and then continues without the call stack, and needs 32 KiB or less at every limit.
|
||||
|
||||
Indented output and flattened keys grow with the depth
|
||||
|
||||
Some results are larger than the value by a factor of its nesting depth. [`dump`](https://json.nlohmann.me/api/basic_json/dump/index.md) with an `indent` of `n` (and likewise `operator<<` with `std::setw(n)` and [`basic_json_view::dump`](https://json.nlohmann.me/api/basic_json_view/dump/index.md)) writes up to `n` characters per nesting level in front of every line, and [`flatten`](https://json.nlohmann.me/api/basic_json/flatten/index.md) repeats the path of every value in its key. For the 80,001-byte array `[1,[1,...[1,1]...]]` with 20,000 levels, `dump(1)` returns 600 MB, `dump(4)` 2.4 GB, and the keys of `flatten()` hold 400 MB. A compact `dump()` without indentation stays the size of the value. If you pretty-print, log, or flatten untrusted input, limit its nesting depth while parsing, for example with a [parser callback](https://json.nlohmann.me/features/parsing/parser_callbacks/#recipe-max-nesting-depth-via-a-callback): with a limit of `d`, every line has at most `n * d` indentation characters, and every flattened key has at most `d` reference tokens. [`JSON_RECURSION_DEPTH_LIMIT`](https://json.nlohmann.me/api/macros/json_recursion_depth_limit/index.md) does not help here: it changes only how much of the call stack a walk uses, never its result, and it does not limit the depth that `parse()` accepts.
|
||||
|
||||
## Input size
|
||||
|
||||
The library does not limit the overall size of a JSON text; a value nested or wide enough will use memory proportional to the input. If you parse untrusted input of unbounded size, check the size of the file or stream yourself before — or while — handing it to `parse()`.
|
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@@ -60,6 +64,10 @@ Parsing is not the only place invalid UTF-8 matters: a string that reached a `js
|
||||
|
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The JSON specification leaves the handling of repeated keys in an object up to the implementation, and this library does too: as described in [`object_t`](https://json.nlohmann.me/api/basic_json/object_t/#behavior), it is unspecified which of the values for a repeated key ends up in the parsed object. If your application must reject duplicate keys instead of silently resolving them one way or another, see the [parser callback recipe for rejecting duplicate keys](https://json.nlohmann.me/features/parsing/parser_callbacks/#recipe-rejecting-duplicate-object-keys).
|
||||
|
||||
## Objects with many keys in `ordered_json`
|
||||
|
||||
[`ordered_json`](https://json.nlohmann.me/api/ordered_json/index.md) keeps the members of an object in a vector in insertion order ([`ordered_map`](https://json.nlohmann.me/api/ordered_map/index.md)) and finds a key by searching all members. Parsing JSON text into an `ordered_json` avoids that search for objects with many keys and takes linear time. The binary readers ([`from_cbor`](https://json.nlohmann.me/api/basic_json/from_cbor/index.md), [`from_msgpack`](https://json.nlohmann.me/api/basic_json/from_msgpack/index.md), [`from_ubjson`](https://json.nlohmann.me/api/basic_json/from_ubjson/index.md), [`from_bjdata`](https://json.nlohmann.me/api/basic_json/from_bjdata/index.md), [`from_bson`](https://json.nlohmann.me/api/basic_json/from_bson/index.md), and [`from_bon8`](https://json.nlohmann.me/api/basic_json/from_bon8/index.md)) do not yet: reading an object of `n` keys into an `ordered_json` costs time proportional to `n²`. A flat object of 40,000 keys (about 300 KB of CBOR) takes about 1.3 s, against a few milliseconds as JSON text or into a `json` ([#6104](https://github.com/nlohmann/json/issues/6104)). `json` is not affected. If you read untrusted binary input into `ordered_json`, bound the input size more tightly, read it into a `json`, or reject objects with many keys in a [SAX handler](https://json.nlohmann.me/features/parsing/sax_interface/index.md).
|
||||
|
||||
## Numbers
|
||||
|
||||
A number whose value cannot be represented — for instance `1E1000`, which overflows `double` — is rejected while parsing as [`out_of_range.406`](https://json.nlohmann.me/home/exceptions/#jsonexceptionout_of_range406) rather than silently becoming infinity. An integer that is syntactically valid but does not fit the 64-bit integer types is not rejected; it is instead stored as a `double`, which may lose precision for very large values. See [number limits](https://json.nlohmann.me/features/types/number_handling/#number-limits) for the exact ranges and an example.
|
||||
@@ -75,7 +83,8 @@ A [JSON Pointer](https://json.nlohmann.me/features/json_pointer/index.md) can co
|
||||
## Checklist
|
||||
|
||||
- Wrap parsing in a `try`/`catch` block, or use `allow_exceptions=false`/`accept()` if your environment cannot use exceptions; never let `JSON_NOEXCEPTION`'s `abort()` be the first time you think about error handling.
|
||||
- If the input's nesting depth matters to you, enforce your own limit with a [parser callback](https://json.nlohmann.me/features/parsing/parser_callbacks/#recipe-max-nesting-depth-via-a-callback) or a [SAX handler](https://json.nlohmann.me/features/parsing/sax_interface/index.md); the library bounds the call stack but not memory use.
|
||||
- If the input's nesting depth matters to you (for example because you pretty-print, log, or flatten it), enforce your own limit with a [parser callback](https://json.nlohmann.me/features/parsing/parser_callbacks/#recipe-max-nesting-depth-via-a-callback) or a [SAX handler](https://json.nlohmann.me/features/parsing/sax_interface/index.md); the library bounds the call stack but not memory use.
|
||||
- If you read untrusted binary input into `ordered_json`, mind that objects with many keys are [slow to read](#objects-with-many-keys-in-ordered_json).
|
||||
- Bound the size of the input itself before parsing, independent of the library's own bounded allocations for binary format lengths.
|
||||
- Decide up front how you want a string with invalid UTF-8 — from any source, not only parsing — to be serialized (`strict`, `replace`, or `ignore`), rather than discovering it from an uncaught `type_error.316`.
|
||||
- For untrusted input in a binary format, pass `error_handler_t::strict` to the `from_*` function if the strings must be valid UTF-8; by default they are not checked (BON8 always checks).
|
||||
|
||||
Reference in new issue
Block a user