1 files changed, 146 insertions, 0 deletions
diff --git a/isutf8.c b/isutf8.c
new file mode 100644
index 0000000..88bb38b
--- /dev/null
+++ b/isutf8.c
@@ -0,0 +1,146 @@
+/*
+ * isutf8.c - do the input files look like valid utf-8 byte streams?
+ * 
+ * Copyright (C) 2005  Lars Wirzenius
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <getopt.h>
+
+#define VERSION "1.0"
+
+/* 
+ * I'm pretty sure there is a fancy trick to do this without a loop,
+ * but I'm too tired to figure it out now. --liw
+ */
+static int high_ones(int c)
+{
+    int n;
+
+    for (n = 0; (c & 0x80) == 0x80; c <<= 1)
+        ++n;    
+    return n;
+}
+
+static int is_utf8_byte_stream(FILE *file, char *filename, int quiet)
+{
+    int c, n, remaining_bytes;
+    unsigned long line, col;
+    
+    remaining_bytes = 0;
+    line = 1;
+    col = 1;
+    while ((c = getc(file)) != EOF) {
+        n = high_ones(c);
+        if (remaining_bytes > 0) {
+            if (n == 1) {
+                --remaining_bytes;
+                if (remaining_bytes == 0)
+                    ++col;
+            } else
+                goto error;
+        } else if (n == 0) {
+            /* 7-bit character, skip, but adjust position */
+            if (c == '\n') {
+                ++line;
+                col = 1;
+            } else
+                ++col;
+        } else if (n == 1)
+            goto error; /* wrong place for continuation byte */
+        else
+            remaining_bytes = n - 1; /* start of multi-byte sequence */
+    }
+    if (remaining_bytes > 0)
+        goto error;
+    return 1;
+    
+error:
+    if (!quiet) {
+        printf("%s: line %lu, col %lu: invalid UTF-8 code\n", 
+               filename, line, col);
+    }
+    return 0;
+}
+
+static void usage(const char *program_name)
+{
+    printf("Usage: %s [-hq] [--help] [--quiet] [file ...]\n", program_name);
+    printf("Check whether input files are valid UTF-8.\n");
+    printf("This is version %s.\n", VERSION);
+}
+
+int main(int argc, char **argv)
+{
+    int i, ok;
+    FILE *file;
+
+    int quiet;
+    struct option options[] = {
+        { "help", no_argument, NULL, 'h' },
+        { "quiet", no_argument, &quiet, 1 },
+    };
+    int opt;
+    
+    quiet = 0;
+    
+    while ((opt = getopt_long(argc, argv, "hq", options, NULL)) != -1) {
+        switch (opt) {
+        case 0:
+            break;
+            
+        case 'h':
+            usage(argv[0]);
+            exit(0);
+            break;
+            
+        case 'q':
+            quiet = 1;
+            break;
+
+        case '?':
+            exit(EXIT_FAILURE);
+
+        default:
+            abort();
+        }
+    }
+
+    if (optind == argc)
+        ok = is_utf8_byte_stream(stdin, "stdin", quiet);
+    else {
+        ok = 1;
+        for (i = optind; i < argc; ++i) {
+            file = fopen(argv[i], "r");
+            if (file == NULL) {
+                fprintf(stderr, "isutf8: %s: error %d: %s\n", 
+                        argv[i], errno, strerror(errno));
+                ok = 0;
+            } else {
+                ok = is_utf8_byte_stream(file, argv[i], quiet) && ok;
+                (void) fclose(file);
+            }
+        }
+    }
+    
+    if (ok)
+        exit(0);
+    exit(EXIT_FAILURE);
+}