vo_image: add outdir option

The function checked_mkdir is taken from vo_jpeg, with the error
handling stripped down to a reasonable level.

libvo/vo_image.c

@@ -20,10 +20,14 @@
 #include <string.h>
 #include <math.h>
 #include <stdbool.h>
+#include <sys/stat.h>
 
 #include <libswscale/swscale.h>
 
 #include "config.h"
+#include "bstr.h"
+#include "osdep/io.h"
+#include "path.h"
 #include "talloc.h"
 #include "mp_msg.h"
 #include "libvo/video_out.h"
@@ -37,6 +41,7 @@
 
 struct priv {
     struct image_writer_opts *opts;
+    char *outdir;
 
     int frame;
 
@@ -46,6 +51,24 @@ struct priv {
     struct mp_csp_details colorspace;
 };
 
+static bool checked_mkdir(const char *buf)
+{
+    mp_msg(MSGT_VO, MSGL_INFO, "[vo_image] Creating output directory '%s'...\n",
+           buf);
+    if (mkdir(buf, 0755) < 0) {
+        char *errstr = strerror(errno);
+        if (errno == EEXIST) {
+            struct stat stat_p;
+            if (mp_stat(buf, &stat_p ) == 0 && S_ISDIR(stat_p.st_mode))
+                return true;
+        }
+        mp_msg(MSGT_VO, MSGL_ERR, "[vo_image] Error creating output directory"
+               ": %s\n", errstr);
+        return false;
+    }
+    return true;
+}
+
 static int config(struct vo *vo, uint32_t width, uint32_t height,
                   uint32_t d_width, uint32_t d_height, uint32_t flags,
                   uint32_t format)
@@ -55,6 +78,10 @@ static int config(struct vo *vo, uint32_t width, uint32_t height,
     p->d_width = d_width;
     p->d_height = d_height;
 
+    if (p->outdir && vo->config_count < 1)
+        if (!checked_mkdir(p->outdir))
+            return -1;
+
     return 0;
 }
 
@@ -74,15 +101,21 @@ static uint32_t draw_image(struct vo *vo, mp_image_t *mpi)
 {
     struct priv *p = vo->priv;
 
-    mp_image_t tmp = *mpi;
-    tmp.width = p->d_width;
-    tmp.height = p->d_height;
+    mp_image_t img = *mpi;
+    img.width = p->d_width;
+    img.height = p->d_height;
 
-    char filename[80];
-    snprintf(filename, sizeof(filename), "%08d.%s", p->frame,
-             image_writer_file_ext(p->opts));
-    mp_msg(MSGT_VO, MSGL_STATUS, "Save %s!\n", filename);
-    write_image(&tmp, &p->colorspace, p->opts, filename);
+    void *t = talloc_new(NULL);
+    char *filename = talloc_asprintf(t, "%08d.%s", p->frame,
+                                     image_writer_file_ext(p->opts));
+
+    if (p->outdir && strlen(p->outdir))
+        filename = mp_path_join(t, bstr0(p->outdir), bstr0(filename));
+
+    mp_msg(MSGT_VO, MSGL_STATUS, "\nSaving %s\n", filename);
+    write_image(&img, &p->colorspace, p->opts, filename);
+
+    talloc_free(t);
 
     (p->frame)++;
 
@@ -151,6 +184,7 @@ const struct vo_driver video_out_image =
     },
     .options = (const struct m_option[]) {
         OPT_SUBSTRUCT(opts, image_writer_conf, M_OPT_MERGE),
+        OPT_STRING("outdir", outdir, 0),
         {0},
     },
     .preinit = preinit,