GUAC-236: Provide -f option for overriding locking behavior.

src/guacenc/encode.c

@@ -34,6 +34,7 @@
 #include <sys/types.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <stdbool.h>
 #include <string.h>
 #include <unistd.h>
 
@@ -84,7 +85,7 @@ static int guacenc_read_instructions(guacenc_display* display,
 }
 
 int guacenc_encode(const char* path, const char* out_path, const char* codec,
-        int width, int height, int bitrate) {
+        int width, int height, int bitrate, bool force) {
 
     /* Open input file */
     int fd = open(path, O_RDONLY);
@@ -103,12 +104,13 @@ int guacenc_encode(const char* path, const char* out_path, const char* codec,
     };
 
     /* Abort if file cannot be locked for reading */
-    if (fcntl(fd, F_SETLK, &file_lock) == -1) {
+    if (!force && fcntl(fd, F_SETLK, &file_lock) == -1) {
 
         /* Warn if lock cannot be acquired */
         if (errno == EACCES || errno == EAGAIN)
             guacenc_log(GUAC_LOG_WARNING, "Refusing to encode in-progress "
-                    "recording \"%s\".", path);
+                    "recording \"%s\" (specify the -f option to override "
+                    "this behavior).", path);
 
         /* Log an error if locking fails in an unexpected way */
         else

src/guacenc/encode.h

@@ -25,8 +25,13 @@
 
 #include "config.h"
 
+#include <stdbool.h>
+
 /**
- * Encodes the given Guacamole protocol dump as video.
+ * Encodes the given Guacamole protocol dump as video. A read lock will be
+ * acquired on the input file to ensure that in-progress recordings are not
+ * encoded. This behavior can be overridden by specifying true for the force
+ * parameter.
  *
  * @param path
  *     The path to the file containing the raw Guacamole protocol dump.
@@ -48,12 +53,16 @@
  *     The desired overall bitrate of the resulting encoded video, in bits per
  *     second.
  *
+ * @param force
+ *     Perform the encoding, even if the input file appears to be an
+ *     in-progress recording (has an associated lock).
+ *
  * @return
  *     Zero on success, non-zero if an error prevented successful encoding of
  *     the video.
  */
 int guacenc_encode(const char* path, const char* out_path, const char* codec,
-        int width, int height, int bitrate);
+        int width, int height, int bitrate, bool force);
 
 #endif
 

src/guacenc/guacenc.c

@@ -30,6 +30,7 @@
 #include <libavcodec/avcodec.h>
 
 #include <getopt.h>
+#include <stdbool.h>
 #include <stdio.h>
 
 int main(int argc, char* argv[]) {
@@ -37,13 +38,14 @@ int main(int argc, char* argv[]) {
     int i;
 
     /* Load defaults */
+    bool force = false;
     int width = GUACENC_DEFAULT_WIDTH;
     int height = GUACENC_DEFAULT_HEIGHT;
     int bitrate = GUACENC_DEFAULT_BITRATE;
 
     /* Parse arguments */
     int opt;
-    while ((opt = getopt(argc, argv, "s:r:")) != -1) {
+    while ((opt = getopt(argc, argv, "s:r:f")) != -1) {
 
         /* -s: Dimensions (WIDTHxHEIGHT) */
         if (opt == 's') {
@@ -61,6 +63,10 @@ int main(int argc, char* argv[]) {
             }
         }
 
+        /* -f: Force */
+        else if (opt == 'f')
+            force = true;
+
         /* Invalid option */
         else {
             goto invalid_options;
@@ -108,7 +114,8 @@ int main(int argc, char* argv[]) {
         }
 
         /* Attempt encoding, log granular success/failure at debug level */
-        if (guacenc_encode(path, out_path, "mpeg4", width, height, bitrate)) {
+        if (guacenc_encode(path, out_path, "mpeg4",
+                    width, height, bitrate, force)) {
             failures++;
             guacenc_log(GUAC_LOG_DEBUG,
                     "%s was NOT successfully encoded.", path);
@@ -136,6 +143,7 @@ invalid_options:
     fprintf(stderr, "USAGE: %s"
             " [-s WIDTHxHEIGHT]"
             " [-r BITRATE]"
+            " [-f]"
             " [FILE]...\n", argv[0]);
 
     return 1;

src/guacenc/man/guacenc.1

@@ -7,6 +7,7 @@ guacenc \- Guacamole video encoder
 .B guacenc
 [\fB-s\fR \fIWIDTH\fRx\fIHEIGHT\fR]
 [\fB-r\fR \fIBITRATE\fR]
+[\fB-f\fR]
 [\fIFILE\fR]...
 .
 .SH DESCRIPTION
@@ -23,7 +24,18 @@ Each \fIFILE\fR specified will be encoded as a raw MPEG-4 video stream to a new
 file named \fIFILE\fR.m4v, encoded according to the other options specified. By
 default, the output video will be \fI640\fRx\fI480\fR pixels, and will be saved
 with a bitrate of \fI2000000\fR bits per second (2 Mbps). These defaults can be
-overridden with the \fB-s\fR and \fB-r\fR options respectively.
+overridden with the \fB-s\fR and \fB-r\fR options respectively. Existing files
+will not be overwritten; the encoding process for any input file will be
+aborted if it would result in overwriting an existing file.
+.P
+Guacamole acquires a write lock on recordings as they are being written. By
+default,
+.B guacenc
+will check whether the each input file is locked and will refuse to read and
+encode an input file if it appears to be an in-progress recording. This
+behavior can be overridden by specifying the \fB-f\fR option. Encoding an
+in-progress recording will still result in a valid video; the video will simply
+cover the user's session only up to the current point in time.
 .
 .SH OPTIONS
 .TP
@@ -39,6 +51,12 @@ will use for the saved video. This is specified in bits per second. By default,
 this will be \fI2000000\fR (2 Mbps). Higher values will result in larger but
 higher-quality video files. Lower values will result in smaller but
 lower-quality video files.
+.TP
+\fB-f\fR
+Overrides the default behavior of
+.B guacenc
+such that input files will be encoded even if they appear to be recordings of
+in-progress Guacamole sessions.
 .
 .SH AUTHOR
 Written by Michael Jumper <mike.jumper@guac-dev.org>