X-Git-Url: http://git.scottworley.com/tl-append/blobdiff_plain/d19cfb47a757887f104a3b2a659ee288083d88af..c89c80109bffaaaf40a828bfe883277dbecc0eb5:/tl-append.c

diff --git a/tl-append.c b/tl-append.c
index 6cc068a..8b0da57 100644
--- a/tl-append.c
+++ b/tl-append.c
@@ -1,3 +1,20 @@
+/*
+ * tl-append: time-logger appending shell
+ * Copyright (C) 2023  Scott Worley <scottworley@scottworley.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
 #define _POSIX_C_SOURCE 199309L
 
 #include <errno.h>
@@ -5,6 +22,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/file.h>
 #include <time.h>
 #include <unistd.h>
 
@@ -21,15 +39,35 @@ const struct timespec ACKNOWLEDGE_DELAY = {0, 300000000};
 
 typedef struct {
   int interactive;
+  int fcntl_lock;
+  int flock_lock;
 } conf_t;
 
+void usage() {
+  die("usage: tl-append [-i] [-C dir] [--no-fnctl-lock] [--no-flock-lock]");
+}
+
 conf_t parse_command_line(int argc, char *argv[]) {
   conf_t conf;
   conf.interactive = 0;
+  conf.fcntl_lock = 1;
+  conf.flock_lock = 1;
 
   for (int i = 1; i < argc; i++) {
     if (strcmp(argv[i], "-i") == 0 && isatty(2))
       conf.interactive = 1;
+    else if (strcmp(argv[i], "--no-fnctl-lock") == 0)
+      conf.fcntl_lock = 0;
+    else if (strcmp(argv[i], "--no-flock-lock") == 0)
+      conf.flock_lock = 0;
+    else if (strcmp(argv[i], "-C") == 0) {
+      if (i + 1 >= argc)
+        die("-C requires a directory");
+      if (chdir(argv[i + 1]) == -1)
+        die_err("Couldn't change directory");
+      i++;
+    } else
+      usage();
   }
 
   return conf;
@@ -61,7 +99,9 @@ static void write_line(const char *now, FILE *f, const char *line) {
     die("Error writing to output file");
 }
 
-static void take_lock(FILE *f) {
+static void take_fcntl_lock(conf_t *conf, FILE *f) {
+  if (!conf->fcntl_lock)
+    return;
   struct flock lock;
   lock.l_type = F_WRLCK;
   lock.l_whence = SEEK_SET;
@@ -73,12 +113,34 @@ static void take_lock(FILE *f) {
   if (fcntl(fd, F_SETLK, &lock) == 0)
     return;
   if (errno != EACCES && errno != EAGAIN)
-    die_err("Couldn't take lock");
+    die_err("Couldn't take fcntl lock");
   if (fputs(WAITING, stderr) == EOF)
     die("Error writing waiting message");
   if (fcntl(fd, F_SETLKW, &lock) == 0)
     return;
-  die_err("Couldn't take lock");
+  die_err("Couldn't take fcntl lock");
+}
+
+static void take_flock_lock(conf_t *conf, FILE *f) {
+  if (!conf->flock_lock)
+    return;
+  int fd = fileno(f);
+  if (fd == -1)
+    die_err("Couldn't get file descriptor for locking");
+  if (flock(fd, LOCK_EX | LOCK_NB) == 0)
+    return;
+  if (errno != EWOULDBLOCK)
+    die_err("Couldn't take flock lock");
+  if (fputs(WAITING, stderr) == EOF)
+    die("Error writing waiting message");
+  if (flock(fd, LOCK_EX) == 0)
+    return;
+  die_err("Couldn't take flock lock");
+}
+
+static void take_lock(conf_t *conf, FILE *f) {
+  take_fcntl_lock(conf, f);
+  take_flock_lock(conf, f);
 }
 
 static void write_acknowledgment(conf_t *conf) {
@@ -91,15 +153,16 @@ static void write_acknowledgment(conf_t *conf) {
 }
 
 static void lock_and_write_line(conf_t *conf, const char *line) {
-  const char *now = encode_time(time(NULL));
+  char *now = encode_time(time(NULL));
   FILE *f = fopen(FILENAME, "a");
 
-  take_lock(f);
+  take_lock(conf, f);
   write_line(now, f, line);
 
   if (fclose(f) != 0)
     die_err("Error closing output file");
 
+  free(now);
   write_acknowledgment(conf);
 }