diff options
Diffstat (limited to 'tcpdump.c')
| -rw-r--r-- | tcpdump.c | 22 |
1 files changed, 20 insertions, 2 deletions
@@ -843,6 +843,8 @@ MakeFilename(char *buffer, char *orig_name, int cnt, int max_chars) char *filename = malloc(PATH_MAX + 1); if (filename == NULL) error("%s: malloc", __func__); + if (strlen(orig_name) == 0) + error("an empty string is not a valid file name"); /* Process with strftime if Gflag is set. */ if (Gflag != 0) { @@ -854,9 +856,25 @@ MakeFilename(char *buffer, char *orig_name, int cnt, int max_chars) } /* There's no good way to detect an error in strftime since a return - * value of 0 isn't necessarily failure. + * value of 0 isn't necessarily failure; if orig_name is an empty + * string, the formatted string will be empty. + * + * However, the C90 standard says that, if there *is* a + * buffer overflow, the content of the buffer is undefined, + * so we must check for a buffer overflow. + * + * So we check above for an empty orig_name, and only call + * strftime() if it's non-empty, in which case the return + * value will only be 0 if the formatted date doesn't fit + * in the buffer. + * + * (We check above because, even if we don't use -G, we + * want a better error message than "tcpdump: : No such + * file or directory" for this case.) */ - strftime(filename, PATH_MAX, orig_name, local_tm); + if (strftime(filename, PATH_MAX, orig_name, local_tm) == 0) { + error("%s: strftime", __func__); + } } else { strncpy(filename, orig_name, PATH_MAX); } |