util: Add pgm_read function

2 files changed, 44 insertions, 0 deletions

diff --git a/src/util.c b/src/util.c
index 8b73466..7b7077d 100644
--- a/src/util.c
+++ b/src/util.c
@@ -1,9 +1,50 @@
+#define _XOPEN_SOURCE 700
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
 
 #include "video_decode.h"
 #include "util.h"
 
 int
+pgm_read(char *filename, unsigned char **buf, int *xsize, int *ysize)
+{
+	FILE *f = NULL;
+	unsigned char *b = NULL;
+	int width, height;
+	ssize_t n;
+
+	f = fopen(filename, "r");
+	if (f == NULL)
+		return -1;
+
+	if (fscanf(f, "P5\n%d %d\n255\n", &width, &height) == 0)
+		return -1;
+
+	if (width * height <= 0)
+		goto fail;
+
+	if ((b = malloc(width * height)) == NULL)
+		goto fail;
+	if ((n = fread(b, 1, width * height, f)) == 0 || n != width * height)
+		goto fail;
+
+	fclose(f);
+
+	*buf = b;
+	*xsize = width;
+	*ysize = height;
+
+	return 0;
+
+fail:
+	if (f) fclose(f);
+	if (b) free(b);
+	return -1;
+}
+
+int
 pgm_save(unsigned char *buf, int wrap, int xsize, int ysize, char *filename)
 {
 	FILE *f;
diff --git a/src/util.h b/src/util.h
index 649e9ee..5921a86 100644
--- a/src/util.h
+++ b/src/util.h
@@ -4,6 +4,9 @@
 #include <stdint.h>
 
 int
+pgm_read(char *filename, unsigned char **buf, int *xsize, int *ysize);
+
+int
 pgm_save(unsigned char *buf, int wrap, int xsize, int ysize, char *filename);
 
 /* Store half of frame_a and half of frame_b in frame_a */