| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | #include <errno.h> | ||
| 2 | #include <stdio.h> | ||
| 3 | #include "xsnprintf.h" | ||
| 4 | #include "debug.h" | ||
| 5 | |||
| 6 | /* | ||
| 7 | * ISO C doesn't require vsnprintf(3) to set errno on failure, but | ||
| 8 | * POSIX does: | ||
| 9 | * | ||
| 10 | * "If an output error was encountered, these functions shall return | ||
| 11 | * a negative value and set errno to indicate the error." | ||
| 12 | * | ||
| 13 | * The mandated errors of interest are: | ||
| 14 | * | ||
| 15 | * • EILSEQ: A wide-character code does not correspond to a valid character | ||
| 16 | * • EOVERFLOW: The value of n is greater than INT_MAX | ||
| 17 | * • EOVERFLOW: The value to be returned is greater than INT_MAX | ||
| 18 | * | ||
| 19 | * ISO C11 states: | ||
| 20 | * | ||
| 21 | * "The vsnprintf function returns the number of characters that would | ||
| 22 | * have been written had n been sufficiently large, not counting the | ||
| 23 | * terminating null character, or a negative value if an encoding error | ||
| 24 | * occurred. Thus, the null-terminated output has been completely | ||
| 25 | * written if and only if the returned value is nonnegative and less | ||
| 26 | * than n." | ||
| 27 | * | ||
| 28 | * See also: | ||
| 29 | * | ||
| 30 | * • ISO C11 §7.21.6.12p3 | ||
| 31 | * • https://pubs.opengroup.org/onlinepubs/9699919799/functions/vsnprintf.html | ||
| 32 | * • https://pubs.opengroup.org/onlinepubs/9699919799/functions/snprintf.html | ||
| 33 | */ | ||
| 34 | 5530 | size_t xvsnprintf(char *restrict buf, size_t n, const char *restrict fmt, va_list v) | |
| 35 | { | ||
| 36 | 5530 | int r = vsnprintf(buf, n, fmt, v); | |
| 37 |
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5530 | FATAL_ERROR_ON(r < 0 || r >= (int)n, r < 0 ? errno : ENOBUFS); |
| 38 | 5530 | return (size_t)r; | |
| 39 | } | ||
| 40 | |||
| 41 | 5528 | size_t xsnprintf(char *restrict buf, size_t n, const char *restrict fmt, ...) | |
| 42 | { | ||
| 43 | 5528 | va_list v; | |
| 44 | 5528 | va_start(v, fmt); | |
| 45 | 5528 | size_t r = xvsnprintf(buf, n, fmt, v); | |
| 46 | 5528 | va_end(v); | |
| 47 | 5528 | return r; | |
| 48 | } | ||
| 49 |