fdec47f63f
Introduce a macro for handling common case of partial writes to a character array. * xstring.h (get_pos_diff_): New function. (xappendstr): New macro.
107 lines
3.1 KiB
C
107 lines
3.1 KiB
C
#ifndef STRACE_XSTRING_H
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#define STRACE_XSTRING_H
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#include <stdarg.h>
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#include <stdio.h>
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#include "error_prints.h"
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#include "gcc_compat.h"
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/**
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* Print to static buffer and die on (really unexpected) errors and overflows.
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* Shouldn't be used directly; please refer to helper macros xsnprintf and
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* xsprint instead.
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*
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* @param str String buffer to print into.
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* @param size Size of the string buffer in bytes.
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* @param func Function name from which this function is called.
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* @param argstr Stringified arguments (including format argument).
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* @param format Format string.
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* @param ... Format arguments.
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* @return Number of characters printed, excluding terminating null byte
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* (the same as s(n)printf).
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*/
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static inline int ATTRIBUTE_FORMAT((printf, 5, 6))
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xsnprintf_(char *str, size_t size, const char *func, const char *argstr,
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const char *format, ...)
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{
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int ret;
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va_list ap;
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va_start(ap, format);
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ret = vsnprintf(str, size, format, ap);
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va_end(ap);
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if (ret < 0 || (unsigned int) ret >= size)
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error_msg_and_die("%s: got unexpected return value %d for "
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"snprintf(buf, %zu, %s)",
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func, ret, size, argstr);
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return ret;
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}
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/**
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* snprintf that dies on (really unexpected) errors and overflows.
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*
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* @param str_ String buffer to print into.
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* @param size_ Size of the string buffer in bytes.
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* @param fmt_ Format string.
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* @param ... Format arguments.
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*/
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#define xsnprintf(str_, size_, fmt_, ...) \
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xsnprintf_((str_), (size_), __func__, #fmt_ ", " #__VA_ARGS__, \
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(fmt_), __VA_ARGS__)
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/**
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* Print to a character array buffer and die on (really unexpected) errors and
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* overflows. Buffer size is obtained with sizeof().
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*
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* @param str_ Character array buffer to print into.
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* @param fmt_ Format string.
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* @param ... Format arguments.
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*/
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#define xsprintf(str_, fmt_, ...) \
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xsnprintf((str_), sizeof(str_) + MUST_BE_ARRAY(str_), (fmt_), \
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__VA_ARGS__)
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static inline size_t
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get_pos_diff_(char *str, size_t size, char *pos, const char *func,
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const char *call)
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{
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if ((str + size) < str)
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error_msg_and_die("%s: string size overflow (%p+%zu) in %s",
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func, str, size, call);
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if (pos > (str + size))
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error_msg_and_die("%s: got position (%p) beyond string "
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"(%p+%zu) in %s",
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func, pos, str, size, call);
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if (pos < str)
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error_msg_and_die("%s: got position %p before string %p in %s",
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func, pos, str, call);
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return pos - str;
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}
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/**
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* Helper function for constructing string in a character array by appending
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* new formatted parts. Returns new position. In aligment with the rest of x*
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* functions, fails on error or buffer overflow. Obtains buffer size via
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* sizeof(str_).
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*
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* @param str_ Character array buffer to print into.
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* @param pos_ Current position.
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* @param fmt_ Format string.
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* @param ... Format arguments.
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* @return New position.
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*/
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#define xappendstr(str_, pos_, fmt_, ...) \
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(xsnprintf((pos_), sizeof(str_) + MUST_BE_ARRAY(str_) - \
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get_pos_diff_((str_), sizeof(str_), (pos_), __func__, \
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"xappendstr(" #str_ ", " #pos_ ", " #fmt_ ", " \
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#__VA_ARGS__ ")"), \
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(fmt_), ##__VA_ARGS__) + (pos_))
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#endif /* !STRACE_XSTRING_H */
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