diff options
Diffstat (limited to '')
| -rw-r--r-- | vweprintf.c | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/vweprintf.c b/vweprintf.c new file mode 100644 index 0000000..605f1c2 --- /dev/null +++ b/vweprintf.c @@ -0,0 +1,56 @@ +/* See LICENSE file for copyright and license details. */ +#include "libsimple.h" + + +extern char *argv0; + + +void +vweprintf(const char *fmt, va_list ap) +{ + int saved_errno = errno, r; + const char *end = strchr(fmt, '\0'); + const char *prefix1 = argv0; + const char *prefix2 = ": "; + const char *suffix1 = ""; + const char *suffix2 = ""; + const char *suffix3 = ""; + char *message = NULL; + va_list ap1; + va_list ap2; + + if (!argv0 || !strncmp(fmt, "usage: ", strlen("usage: "))) + prefix1 = prefix2 = ""; + + va_copy(ap1, ap); + va_copy(ap2, ap); + r = vsnprintf(NULL, 0, fmt, ap1); + if (0 <= r && (size_t)r < SIZE_MAX) { + message = alloca((size_t)r + 1); + vsprintf(message, fmt, ap2); + } + va_end(ap2); + va_end(ap1); + + if (!*fmt) { + suffix1 = strerror(saved_errno); + suffix2 = "\n"; + } else if (end[-1] == ':') { + suffix1 = " "; + suffix2 = strerror(saved_errno); + suffix3 = "\n"; + } else if (end[-1] != '\n') { + suffix1 = "\n"; + } + + if (message) { + /* This is to avoid mangling when multiple processes are writting. */ + fprintf(stderr, "%s%s%s%s%s%s", prefix1, prefix2, message, suffix1, suffix2, suffix3); + } else { + fprintf(stderr, "%s%s", prefix1, prefix2); + vfprintf(stderr, fmt, ap); + fprintf(stderr, "%s%s%s", suffix1, suffix2, suffix3); + } + + errno = saved_errno; +} |