d5c738c608
Designed to aid converting off from sscanf parsers. sscanf is hard to use right, easy to mess up and often makes for sloppy error checking. The new parsers allow more exact and pedandic parsing. This new set of functions should be possible to use (and extend) and switch over other libcurl parser code to use going forward. Adapts the following to use the new functions: - altsvc.c - hsts.c - http_aws_sigv4.c Bonus: fewer memory copies, fewer stack buffers. Test: Unit test1664 Docs: docs/internals/STRPARSE.md Closes #15692
110 lines
2.5 KiB
Markdown
110 lines
2.5 KiB
Markdown
<!--
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Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
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SPDX-License-Identifier: curl
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-->
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# String parsing with `strparse`
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The functions take input via a pointer to a pointer, which allows the
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functions to advance the pointer on success which then by extension allows
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"chaining" of functions like this example that gets a word, a space and then a
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second word:
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~~~c
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if(Curl_str_word(&line, &word1, MAX) ||
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Curl_str_singlespace(&line) ||
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Curl_str_word(&line, &word2, MAX))
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fprintf(stderr, "ERROR\n");
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~~~
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## Strings
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The functions that return string information does so by populating a
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`struct Curl_str`:
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~~~c
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struct Curl_str {
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char *str;
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size_t len;
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};
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~~~
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## `Curl_str_word`
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~~~c
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int Curl_str_word(char **linep, struct Curl_str *out, const size_t max);
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~~~
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Get a sequence of bytes until the first space or the end of the string. Return
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non-zero on error. There is no way to include a space in the word, no sort of
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escaping. The word must be at least one byte, otherwise it is considered an
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error.
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`max` is the longest accepted word, or it returns error.
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On a successful return, `linep` is updated to point to the byte immediately
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following the parsed word.
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## `Curl_str_until`
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~~~c
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int Curl_str_until(char **linep, struct Curl_str *out, const size_t max,
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char delim);
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~~~
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Like `Curl_str_word` but instead of parsing to space, it parses to a given
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custom delimiter non-zero byte `delim`.
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`max` is the longest accepted word, or it returns error.
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The parsed word must be at least one byte, otherwise it is considered an
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error.
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## `Curl_str_quotedword`
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~~~c
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int Curl_str_quotedword(char **linep, struct Curl_str *out, const size_t max);
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~~~
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Get a "quoted" word. This means everything that is provided within a leading
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and an ending double character. No escaping possible.
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`max` is the longest accepted word, or it returns error.
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The parsed word must be at least one byte, otherwise it is considered an
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error.
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## `Curl_str_single`
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~~~c
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int Curl_str_single(char **linep, char byte);
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~~~
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Advance over a single character provided in `byte`. Return non-zero on error.
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## `Curl_str_singlespace`
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~~~c
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int Curl_str_singlespace(char **linep);
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~~~
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Advance over a single ASCII space. Return non-zero on error.
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## `Curl_str_number`
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~~~c
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int Curl_str_number(char **linep, size_t *nump, size_t max);
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~~~
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Get an unsigned decimal number. Leading zeroes are just swallowed. Return
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non-zero on error.
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## `Curl_str_newline`
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~~~c
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int Curl_str_newline(char **linep);
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~~~
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Check for a single CR or LF. Return non-zero on error */
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