api: add function file_compare (issue #2250)

src/core/core-dir.c

@@ -1431,3 +1431,127 @@ dir_file_compress (const char *filename_input,
         return 0;
     }
 }
+
+/*
+ * Compares the content of two files (the attributes of the files like the
+ * permissions or timestamp are ignored).
+ *
+ * Comparison is done like this:
+ *   1. if sizes are different, return 1 (different content)
+ *   2. if sizes are the same, read both files until a difference is found
+ *
+ * Returns:
+ *   0: both files exist and their content is exactly the same
+ *   1: content is different
+ *   2: other error (file not found, read error)
+ */
+
+int
+dir_file_compare (const char *filename1, const char *filename2)
+{
+    char buffer1[4096], buffer2[4096];
+    FILE *f1, *f2;
+    struct stat st;
+    off_t size1, size2;
+    size_t count1, count2;
+    int rc, eof1, eof2;
+
+    if (!filename1 || !filename1[0] || !filename2 || !filename2[0])
+        return 2;
+
+    rc = 1;
+
+    f1 = NULL;
+    f2 = NULL;
+
+    /* get size of first file */
+    if (access (filename1, R_OK) != 0)
+    {
+        rc = 2;
+        goto end;
+    }
+    if (stat (filename1, &st) != 0)
+    {
+        rc = 2;
+        goto end;
+    }
+    size1 = st.st_size;
+
+    /* get size of second file */
+    if (access (filename2, R_OK) != 0)
+    {
+        rc = 2;
+        goto end;
+    }
+    if (stat (filename2, &st) != 0)
+    {
+        rc = 2;
+        goto end;
+    }
+    size2 = st.st_size;
+
+    if (size1 != size2)
+    {
+        /* different size, so different content */
+        rc = 1;
+        goto end;
+    }
+
+    f1 = fopen (filename1, "r");
+    if (!f1)
+    {
+        rc = 2;
+        goto end;
+    }
+    f2 = fopen (filename2, "r");
+    if (!f2)
+    {
+        rc = 2;
+        goto end;
+    }
+
+    while (1)
+    {
+        eof1 = feof (f1);
+        eof2 = feof (f2);
+        if ((eof1 && !eof2) || (!eof1 && eof2))
+        {
+            /* different content */
+            rc = 1;
+            goto end;
+        }
+        if (eof1 && eof2)
+        {
+            /* same content */
+            rc = 0;
+            goto end;
+        }
+        count1 = fread (buffer1, sizeof (char), sizeof (buffer1), f1);
+        count2 = fread (buffer2, sizeof (char), sizeof (buffer2), f2);
+        if (count1 != count2)
+        {
+            /* different content */
+            rc = 1;
+            goto end;
+        }
+        if ((count1 == 0) || (count2 == 0))
+        {
+            /* read error */
+            rc = 2;
+            goto end;
+        }
+        if (memcmp (buffer1, buffer2, count1) != 0)
+        {
+            /* different content */
+            rc = 1;
+            goto end;
+        }
+    }
+
+end:
+    if (f1)
+	fclose (f1);
+    if (f2)
+        fclose (f2);
+    return rc;
+}

src/core/core-dir.h

@@ -41,5 +41,6 @@ extern char *dir_file_get_content (const char *filename);
 extern int dir_file_copy (const char *from, const char *to);
 extern int dir_file_compress (const char *from, const char *to,
                               const char *compressor, int compression_level);
+extern int dir_file_compare (const char *filename1, const char *filename2);
 
 #endif /* WEECHAT_DIR_H */

src/plugins/plugin.c

@@ -693,6 +693,7 @@ plugin_load (const char *filename, int init_plugin, int argc, char **argv)
         new_plugin->file_get_content = &dir_file_get_content;
         new_plugin->file_copy = &dir_file_copy;
         new_plugin->file_compress = &dir_file_compress;
+        new_plugin->file_compare = &dir_file_compare;
 
         new_plugin->util_timeval_cmp = &util_timeval_cmp;
         new_plugin->util_timeval_diff = &util_timeval_diff;

src/plugins/weechat-plugin.h

@@ -76,7 +76,7 @@ struct t_weelist_item;
  * please change the date with current one; for a second change at same
  * date, increment the 01, otherwise please keep 01.
  */
-#define WEECHAT_PLUGIN_API_VERSION "20250215-01"
+#define WEECHAT_PLUGIN_API_VERSION "20250507-01"
 
 /* macros for defining plugin infos */
 #define WEECHAT_PLUGIN_NAME(__name)                                     \
@@ -457,6 +457,7 @@ struct t_weechat_plugin
     int (*file_copy) (const char *from, const char *to);
     int (*file_compress) (const char *from, const char *to,
                           const char *compressor, int compression_level);
+    int (*file_compare) (const char *filename1, const char *filename2);
 
     /* util */
     int (*util_timeval_cmp) (struct timeval *tv1, struct timeval *tv2);
@@ -1528,6 +1529,8 @@ extern int weechat_plugin_end (struct t_weechat_plugin *plugin);
                               __compression_level)                      \
     (weechat_plugin->file_compress)(__from, __to, __compressor,         \
                                     __compression_level)
+#define weechat_file_compare(__filename1, __filename2)                  \
+    (weechat_plugin->file_compress)(__filename1, __filename2)
 
 /* util */
 #define weechat_util_timeval_cmp(__time1, __time2)                      \