diff options
Diffstat (limited to 'src/mds.c')
| -rw-r--r-- | src/mds.c | 51 |
1 files changed, 50 insertions, 1 deletions
@@ -91,10 +91,59 @@ int main(int argc_, const char** argv_) fd = open(pathname, O_CREAT | O_EXCL); if (fd == -1) { - /* TODO reuse display index not no longer used */ + /* Reuse display index not no longer used. */ + size_t read_len; + f = fopen(pathname, "r"); + if (f == NULL) /* Race, or error? */ + { + perror(*argv); + continue; + } + read_len = read(piddata, 1, sizeof(piddata) / sizeof(char), f); + if (ferror(f)) /* Failed to read. */ + perror(*argv); + else if (feof(f) == 0) /* Did not read everything. */ + fprintf(stderr, + "%s: the content of a PID file is longer than expected.\n", + *argv); + else + { + pid_t pid = 0; + size_t i, n = read_len - 1; + for (i = 0; i < n; i++) + { + char c = piddata[i]; + if (('0' <= c) && (c <= '9')) + pid = pid * 10 + (c & 15); + else + { + fprintf(stderr, + "%s: the content of a PID file is invalid.\n", + *argv); + goto bad; + } + } + if (piddata[n] != '\n') + { + fprintf(stderr, + "%s: the content of a PID file is invalid.\n", + *argv); + goto bad; + } + if (kill(pid, 0) < 0) /* Check if the PID is still allocated to any process. */ + if (errno == ESRCH) /* PID is not used. */ + { + fclose(f); + close(fd); + break; + } + } + bad: + fclose(f); continue; } close(fd); + break; } if (display == DISPLAY_MAX) { |