diff options
Diffstat (limited to 'usage.c')
| -rw-r--r-- | usage.c | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/usage.c b/usage.c index 2fdb20086bd6..58fb5fff5f24 100644 --- a/usage.c +++ b/usage.c @@ -9,14 +9,26 @@ void vreportf(const char *prefix, const char *err, va_list params) { char msg[4096]; - char *p; + char *p, *pend = msg + sizeof(msg); + size_t prefix_len = strlen(prefix); - vsnprintf(msg, sizeof(msg), err, params); - for (p = msg; *p; p++) { + if (sizeof(msg) <= prefix_len) { + fprintf(stderr, "BUG!!! too long a prefix '%s'\n", prefix); + abort(); + } + memcpy(msg, prefix, prefix_len); + p = msg + prefix_len; + if (vsnprintf(p, pend - p, err, params) < 0) + *p = '\0'; /* vsnprintf() failed, clip at prefix */ + + for (; p != pend - 1 && *p; p++) { if (iscntrl(*p) && *p != '\t' && *p != '\n') *p = '?'; } - fprintf(stderr, "%s%s\n", prefix, msg); + + *(p++) = '\n'; /* we no longer need a NUL */ + fflush(stderr); + write_in_full(2, msg, p - msg); } static NORETURN void usage_builtin(const char *err, va_list params) |