split the reading and writing features

stegmp() now receives a file handler as second argument.

if this one is non-null, then it is the file from which we need to read
the input and write it back to the bitmap.

if it is null, then we need to read from the bitmap and display back the
data on the standard output

Signed-off-by: Olivier Gayot <duskcoder@gmail.com>

1 files changed, 65 insertions, 9 deletions

diff --git a/stegmp.c b/stegmp.c
index b1f42a8..c80075c 100644
--- a/stegmp.c
+++ b/stegmp.c
@@ -21,7 +21,10 @@
 #include <sys/stat.h>
 #include <unistd.h>
 
+#include <sysexits.h>
+
 #include <string.h>
+#include <stdlib.h>
 #include <stdio.h>
 
 #include "bmp.h"
@@ -132,15 +135,18 @@ static int stegmp_parse_headers(const unsigned char *addr, size_t orig_size,
     return 0;
 }
 
-static int stegmp(const char *filename)
+/*
+ * if `input' is NULL, we, want to read bmp_file
+ */
+static int stegmp(const char *bmp_file, FILE *input)
 {
     void *addr;
     struct stat stat;
     struct bitmap bmp;
-    FILE *fh = fopen(filename, "r+");
+    FILE *fh = fopen(bmp_file, "r+");
 
     if (fh == NULL) {
-        fprintf(stderr, "%s: %m\n", filename);
+        fprintf(stderr, "%s: %m\n", bmp_file);
         return -1;
     }
 
@@ -149,14 +155,15 @@ static int stegmp(const char *filename)
             fileno(fh), 0);
 
     if (addr == MAP_FAILED) {
-        fprintf(stderr, "%s: %m\n", filename);
+        fprintf(stderr, "%s: %m\n", bmp_file);
         fclose(fh);
         return -1;
     }
 
     /* retrieve the required information (i.e. width, height, bpp .. ) */
     if (stegmp_parse_headers(addr, stat.st_size, &bmp) >= 0) {
-        /* TODO */
+        (void) input;
+
     } else {
         fprintf(stderr, "unable to parse headers: %s\n",
                 bmp_strerror(bmp_errno));
@@ -168,13 +175,62 @@ static int stegmp(const char *filename)
     return 0;
 }
 
+static inline int stegmp_read(const char *bmp_file)
+{
+    return stegmp(bmp_file, NULL);
+}
+
+static int stegmp_write(const char *bmp_file, const char *in_file)
+{
+    if (strcmp(in_file, "-") == 0) {
+        return stegmp(bmp_file, stdin);
+    } else {
+        int ret;
+        FILE *fh = fopen(in_file, "r");
+
+        if (fh == NULL) {
+            fprintf(stderr, "%s: %m\n", in_file);
+            return -1;
+        }
+
+        ret = stegmp(bmp_file, fh);
+
+        fclose(fh);
+
+        return ret;
+    }
+}
+
+__attribute__((noreturn))
+static void usage(const char *prgnam)
+{
+    fprintf(stderr, "usage: %s COMMAND\n", prgnam);
+    fprintf(stderr, "\nCOMMAND\n");
+    fprintf(stderr, "  read  BMP\n");
+    fprintf(stderr, "  write BMP in_file\n");
+
+    exit(EX_USAGE);
+}
+
 int main(int argc, char *argv[])
 {
     /* we need a file passed as argument since we want to map it */
-    if (argc < 2) {
-        fprintf(stderr, "usage: %s BMP\n", argv[0]);
-        return -1;
+    if (argc < 3) {
+        usage(argv[0]);
     }
 
-    return stegmp(argv[1]);
+    if (strcmp(argv[1], "read") == 0) {
+        /* read */
+
+        return stegmp_read(argv[2]);
+    } else if (strcmp(argv[1], "write") == 0) {
+        /* write */
+        if (argc < 4) {
+            usage(argv[0]);
+        }
+
+        return stegmp_write(argv[2], argv[3]);
+    } else {
+        usage(argv[0]);
+    }
 }