[easytag: 4/4] Rewrite the CRC32 function

[David King <davidk src gnome org>]

commit fac85e3f9a8db097cc4de4af038256e1cc158f08
Author: David King <amigadave amigadave com>
Date:   Mon Jan 14 21:05:03 2013 +0000

    Rewrite the CRC32 function
    
    Simplify the error handling and be more specific about data types.

 src/crc32.c |  202 +++++++++++++++++++++++++++++++++++++++++++----------------
 src/crc32.h |   71 +--------------------
 src/scan.c  |   10 ++--
 3 files changed, 155 insertions(+), 128 deletions(-)
---
diff --git a/src/crc32.c b/src/crc32.c
index 1802195..f7a00b5 100644
--- a/src/crc32.c
+++ b/src/crc32.c
@@ -21,83 +21,179 @@
 #include <sys/stat.h>
 #include <unistd.h>
 #include <stdio.h>
+#include <glib.h>
 #include "crc32.h"
 
+#define BUFFERSIZE 16384   /* (16k) buffer size for reading from the file */
+
+/* TODO: Use GChecksum if https://bugzilla.gnome.org/show_bug.cgi?id=523149
+ * is fixed and CRC32 support is added to GLib.
+ */
+static const guint32 crc32table[] = {
+  0x00000000, 0x77073096, 0xee0e612c, 0x990951ba,
+  0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
+  0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
+  0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
+  0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
+  0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
+  0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec,
+  0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
+  0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
+  0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
+  0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940,
+  0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
+  0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116,
+  0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
+  0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
+  0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
+  0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a,
+  0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
+  0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818,
+  0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
+  0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
+  0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
+  0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c,
+  0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
+  0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
+  0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
+  0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
+  0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
+  0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086,
+  0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
+  0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4,
+  0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
+  0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
+  0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
+  0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
+  0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
+  0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe,
+  0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
+  0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
+  0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
+  0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252,
+  0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
+  0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60,
+  0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
+  0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
+  0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
+  0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04,
+  0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
+  0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a,
+  0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
+  0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
+  0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
+  0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e,
+  0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
+  0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
+  0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
+  0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
+  0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
+  0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0,
+  0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
+  0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6,
+  0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
+  0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
+  0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
+};
+
 /*
- * Calculate the CRC-32 value of audio data (doesn't read the ID3v2 and ID3v1 tags).
- * Return 0 if OK
+ * crc32_file_with_ID3_tag:
+ * @filename: (type filename): an absolute path
+ * @main_val: (out): the CRC32 value
+ *
+ * Calculate the CRC32 value of audio data (skips the ID3v2 and ID3v1 tags).
+ *
+ * Returns: %TRUE if the CRC calculation was sucessful, %FALSE otherwise
  */
-int crc32_file_with_ID3_tag(char *filename, unsigned long *main_val)
+gboolean
+crc32_file_with_ID3_tag (gchar *filename, guint32 *crc32)
 {
-    char          buf[BUFFERSIZE], *p;
-    int           nr;
-    unsigned long crc = ~0, crc32_total = ~0;
-    FILE         *fd;
-    unsigned char tmp_id3[4];
-    int           id3v2size = 0;
-    struct        stat statbuf;
-    unsigned long size = 0;
-    int           has_id3v1 = 0;
-
-
-    if (!filename)
-        return 1;
-
-    stat(filename,&statbuf);
+    gchar buf[BUFFERSIZE], *p;
+    gint nr;
+    guint32 crc = ~0, crc32_total = ~0;
+    FILE *fd;
+    guchar tmp_id3[4];
+    glong id3v2size = 0;
+    struct stat statbuf;
+    off_t size;
+    gboolean has_id3v1 = FALSE;
+
+    g_return_val_if_fail (filename != NULL, FALSE);
+
+    stat (filename, &statbuf);
     size = statbuf.st_size;
 
-    if ( (fd = fopen(filename,"r"))==NULL )
-        return 1;
+    if ((fd = fopen (filename, "r")) == NULL)
+    {
+        goto error;
+    }
 
-    // Check if there is an ID3v1 tag...
-    fseek(fd, -128, SEEK_END);
-    if (fread(tmp_id3, 1, 3, fd) != 3)
-        return 1;
+    /* Check if there is an ID3v1 tag. */
+    fseek (fd, -128, SEEK_END);
+    if (fread (tmp_id3, 1, 3, fd) != 3)
+    {
+        goto error;
+    }
     if (tmp_id3[0] == 'T' && tmp_id3[1] == 'A' && tmp_id3[2] == 'G')
-        has_id3v1 = 1;
-
+    {
+        has_id3v1 = TRUE;
+    }
 
-    // Check if there is an ID3v2 tag...
-    fseek(fd, 0L, SEEK_SET);
-    if (fread(tmp_id3, 1, 4, fd) != 4)
-        return 1;
-    // Calculate ID3v2 length
-    if (tmp_id3[0] == 'I' && tmp_id3[1] == 'D' && tmp_id3[2] == '3' && tmp_id3[3] < 0xFF)
+    /* Check if there is an ID3v2 tag. */
+    fseek (fd, 0L, SEEK_SET);
+    if (fread (tmp_id3, 1, 4, fd) != 4)
+    {
+        goto error;
+    }
+    /* Calculate ID3v2 length. */
+    if (tmp_id3[0] == 'I' && tmp_id3[1] == 'D' && tmp_id3[2] == '3'
+        && tmp_id3[3] < 0xFF)
     {
-        // id3v2 tag skipeer $49 44 33 yy yy xx zz zz zz zz [zz size]
-        fseek(fd, 2, SEEK_CUR); // Size is 6-9 position
-        if (fread(tmp_id3, 1, 4, fd) != 4)
-            return 1;
-        id3v2size = 10 + ( (long)(tmp_id3[3])        | ((long)(tmp_id3[2]) << 7)
-                        | ((long)(tmp_id3[1]) << 14) | ((long)(tmp_id3[0]) << 21) );
-
-        fseek(fd, id3v2size, SEEK_SET);
+        /* ID3v2 tag skipper $49 44 33 yy yy xx zz zz zz zz [zz size]. */
+        fseek (fd, 2, SEEK_CUR); /* Size is 6-9 position. */
+        if (fread (tmp_id3, 1, 4, fd) != 4)
+        {
+            goto error;
+        }
+        id3v2size = 10 +
+                    ((glong)(tmp_id3[3]) | ((glong)(tmp_id3[2]) << 7) |
+                    ((glong)(tmp_id3[1]) << 14) | ((glong)(tmp_id3[0]) << 21));
+
+        fseek (fd, id3v2size, SEEK_SET);
         size = size - id3v2size;
-    }else
+    }
+    else
     {
-        fseek(fd, 0L, SEEK_SET);
+        fseek (fd, id3v2size, SEEK_SET);
     }
 
-    while ((nr = fread(buf, sizeof(char), sizeof(buf), fd)) > 0)
+    while ((nr = fread (buf, sizeof (gchar), sizeof (buf), fd)) > 0)
     {
-        if (has_id3v1 && nr <= 128) // We are reading end of ID3v1 tag
+        if (has_id3v1 && nr <= 128)
+        /* Reading the end of an ID3v1 tag. */
+        {
             break;
-        if ( has_id3v1 && ((size=size-nr) < 128) ) // ID3v1 tag is in the current buf
+        }
+        if (has_id3v1 && ((size = size - nr) < 128))
+        {
+            /* ID3v1 tag is in the current buf. */
             nr = nr - 128 + size;
+        }
 
         for (p = buf; nr--; ++p)
         {
-            crc = (crc >> 8) ^ crctable[(crc ^ *p) & 0xff];
-            crc32_total = (crc >> 8) ^ crctable[(crc32_total ^ *p) & 0xff];
+            crc = (crc >> 8) ^ crc32table[(crc ^ *p) & 0xff];
+            crc32_total = (crc >> 8) ^ crc32table[(crc32_total ^ *p) & 0xff];
         }
     }
 
-    fclose(fd);
-
-    if (nr < 0)
-        return 1;
+out:
+    fclose (fd);
+    *crc32 = ~crc;
 
-    *main_val = ~crc;
+    return nr < 0;
 
-    return 0;
+error:
+    nr = -1;
+    goto out;
 }
diff --git a/src/crc32.h b/src/crc32.h
index 724d3d5..bf35578 100644
--- a/src/crc32.h
+++ b/src/crc32.h
@@ -22,76 +22,7 @@
 #define __CRC32_H__
 
 
-#define BUFFERSIZE 16384   /* (16k) buffer size for reading from the file */
-
-static const unsigned long crctable[256] = {
-  0x00000000, 0x77073096, 0xee0e612c, 0x990951ba,
-  0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
-  0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
-  0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
-  0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
-  0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
-  0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec,
-  0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
-  0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
-  0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
-  0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940,
-  0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
-  0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116,
-  0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
-  0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
-  0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
-  0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a,
-  0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
-  0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818,
-  0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
-  0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
-  0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
-  0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c,
-  0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
-  0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
-  0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
-  0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
-  0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
-  0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086,
-  0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
-  0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4,
-  0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
-  0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
-  0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
-  0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
-  0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
-  0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe,
-  0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
-  0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
-  0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
-  0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252,
-  0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
-  0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60,
-  0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
-  0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
-  0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
-  0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04,
-  0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
-  0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a,
-  0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
-  0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
-  0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
-  0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e,
-  0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
-  0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
-  0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
-  0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
-  0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
-  0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0,
-  0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
-  0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6,
-  0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
-  0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
-  0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d,
-};
-
-int crc32_file_with_ID3_tag(char *filename, unsigned long *main_val);
+gboolean crc32_file_with_ID3_tag (gchar *filename, guint32 *crc32);
 
 
 #endif /* __CRC32_H__ */
diff --git a/src/scan.c b/src/scan.c
index c210296..22aaede 100644
--- a/src/scan.c
+++ b/src/scan.c
@@ -338,7 +338,7 @@ Scan_Tag_With_Mask (ET_File *ETFile)
     // Set CRC-32 value as default comment (for files with ID3 tag only ;-)
     if (SET_CRC32_COMMENT && (OVERWRITE_TAG_FIELD || FileTag->comment==NULL || strlen(FileTag->comment)==0 ) )
     {
-        gulong crc32_value = 0;
+        guint32 crc32_value;
         gchar *buffer;
         ET_File_Description *ETFileDescription;
 
@@ -346,11 +346,11 @@ Scan_Tag_With_Mask (ET_File *ETFile)
         switch (ETFileDescription->TagType)
         {
             case ID3_TAG:
-                crc32_file_with_ID3_tag( ((File_Name *)((GList *)ETFile->FileNameNew)->data)->value, &crc32_value);
-
-                if (crc32_value > 0)
+                if (crc32_file_with_ID3_tag (((File_Name *)((GList *)ETFile->FileNameNew)->data)->value,
+                                             &crc32_value))
                 {
-                    buffer = g_strdup_printf("%.8lx",crc32_value);
+                    buffer = g_strdup_printf ("%.8" G_GUINT32_FORMAT,
+                                              crc32_value);
                     ET_Set_Field_File_Tag_Item((void *)&FileTag->comment,buffer);
                     g_free(buffer);
                 }