diff options
| -rw-r--r-- | user/tlecarrour/porting_guide_for_dummies.mdwn | 77 |
1 files changed, 52 insertions, 25 deletions
diff --git a/user/tlecarrour/porting_guide_for_dummies.mdwn b/user/tlecarrour/porting_guide_for_dummies.mdwn index 91fdac95..176db195 100644 --- a/user/tlecarrour/porting_guide_for_dummies.mdwn +++ b/user/tlecarrour/porting_guide_for_dummies.mdwn @@ -148,31 +148,31 @@ use a new_buff to check if everything went fine Free buf if realloc failed (and Function to read line (no size limit, ending with "\n") from a file. - +static char *get_line(FILE *f) - +{ - + char *buff = NULL; - + char *new_buff = NULL; - + size_t buff_size = 0; - + size_t last = 0; - + - + while (!feof(f)) { - + buff_size = buff_size ? buff_size * 2 : BUFSIZ; - + new_buff = realloc(buff, buff_size); - + if (new_buff == NULL) { - + free(buff); - + return NULL; - + } - + buff = new_buff; - + if (fgets(buff + last, buff_size - last, f) == NULL) { - + free(buff); - + return NULL; - + } - + last = strlen(buff); - + if (buff[last - 1] == '\n') - + return buff; - + } - + return buff; - +} + static char *get_line(FILE *f) + { + char *buff = NULL; + char *new_buff = NULL; + size_t buff_size = 0; + size_t last = 0; + + while (!feof(f)) { + buff_size = buff_size ? buff_size * 2 : BUFSIZ; + new_buff = realloc(buff, buff_size); + if (new_buff == NULL) { + free(buff); + return NULL; + } + buff = new_buff; + if (fgets(buff + last, buff_size - last, f) == NULL) { + free(buff); + return NULL; + } + last = strlen(buff); + if (buff[last - 1] == '\n') + return buff; + } + return buff; + } ### Proper use of readlink() @@ -201,3 +201,30 @@ Call readlink(), check return value and set the null char in the linkname: ... linkname[sb.st_size] = '\0'; + +### Alternative use of readlink() + +In some cases the above approch doesn't work.for instance when reading from +**/proc/*/exe** on Linux. In this case you can try the following function. +The code comes from [[https://buildsecurityin.us-cert.gov/bsi/articles/knowledge/coding/806-BSI.html]] + + static char *readlink_malloc(const char *filename) + { + int size = 100; + + while (1) { + char *buff = malloc(size); + if (buff == NULL) + return NULL; + int nchars = readlink(filename, buff, size); + if (nchars < 0) + return NULL; + if (nchars < size) { + buff[nchars] = '\0'; + return buff; + } + free (buff); + size *= 2; + } + } + |