commit 466ddf52d252337cc5206058df492fc0030700a0
from: Thomas <bthw@posteo.net>
date: Thu Mar 28 12:12:12 2019 UTC

Initial commit

commit - /dev/null
commit + 466ddf52d252337cc5206058df492fc0030700a0
blob - /dev/null
blob + cd642dcbb0d6b067c63961c428b600b11c354e02 (mode 644)
--- /dev/null
+++ id3r.c
@@ -0,0 +1,20 @@
+#include <stdlib.h>
+
+#include "id3v1.h"
+
+int
+main(int argc, char *argv[])
+{
+    FILE *f;
+
+    if (argc != 2) {
+        fputs("usage: id3r filename\n", stderr);
+
+        exit(EXIT_FAILURE);
+    }
+
+    f = fopen(argv[1], "rb");
+    printid3v1(f);
+
+    return EXIT_SUCCESS;
+}
blob - /dev/null
blob + ed5a5c16e6ad4ca5530d407bf41277af0e61c727 (mode 644)
--- /dev/null
+++ id3v1.c
@@ -0,0 +1,67 @@
+#include <inttypes.h>
+#include <string.h>
+
+#include "id3v1.h"
+
+int
+checkid3v1(FILE *f)
+{
+    /* a buffer for the first 4 bytes of the id3v1 tag + terminating NULL */
+    char buffer[5];
+    uint8_t i;
+
+    /* set the current file pointer to the beginning of where the id3v1 tag should be */
+    /* this is 128 bytes from the back of the file */
+    fseek(f, -128, SEEK_END);
+
+    /* copy the first 3 bytes of the supposed id3v1 tag to the buffer */
+    for (i = 0; i < 4; ++i) {
+        buffer[i] = fgetc(f);
+    }
+    /* add terminating NULL character to the end of the buffer, marking it as a string */
+    buffer[4] = '\0';
+
+    /* if first 3 bytes are "TAG" and the fourth isn't '+' */
+    /* "TAG+" indicates id3v1.1 tag which is different from the id3v1 tag */
+    if(!strcmp(buffer, "TAG") && !buffer[3] == '+') {
+        /* 1 = true; 0 = false */
+        return 1;
+    }
+
+    return 0;
+}
+
+void
+printid3v1(FILE *f)
+{
+    /* the size of a field is a maximum of 30 bytes */
+    char buffer[31];
+
+    buffer[30] = '\0';
+    /* start after the TAG field */
+    fseek(f, -125, SEEK_END);
+
+    /* read 30 bytes for the title */
+    fread(buffer, 30, 1, f);
+    printf("Title: %s\n", buffer);
+
+    /* read 30 bytes for the artist name */
+    fread(buffer, 30, 1, f);
+    printf("Artist: %s\n", buffer);
+
+    /* read 30 bytes for the album name */
+    fread(buffer, 30, 1, f);
+    printf("Album: %s\n", buffer);
+
+    /* read 4 bytes for the year */
+    fread(buffer, 4, 1, f);
+    printf("Year: %s\n", buffer);
+
+    /* read 30 bytes for the comment */
+    fread(buffer, 30, 1, f);
+    printf("Comment: %s\n", buffer);
+
+    /* read 1 byte for the genre */
+    fread(buffer, 1, 1, f);
+    printf("Genre: %d\n", buffer[0]);
+}
blob - /dev/null
blob + a7b60dbd824ddff0e9f1e08702a8ba98d6003d67 (mode 644)
--- /dev/null
+++ id3v1.h
@@ -0,0 +1,9 @@
+#ifndef ID3V1_H
+#define ID3V1_H
+
+#include <stdio.h>
+
+int checkid3v1(FILE *);
+void printid3v1(FILE *);
+
+#endif /* ID3V1_H */