uudecode,base64: code shrink

function                                             old     new   delta
read_base64                                          373     358     -15

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>

diff --git a/coreutils/uudecode.c b/coreutils/uudecode.c
index 207fb0b8d9ef6f0811f372a36364166dec6dd4a9..0da9b098864fb773f1cd43648c58271c921467a2 100644 (file)
--- a/coreutils/uudecode.c
+++ b/coreutils/uudecode.c
@@ -77,18 +77,21 @@ static void read_stduu(FILE *src_stream, FILE *dst_stream)
 
 static void read_base64(FILE *src_stream, FILE *dst_stream)
 {
-       int term_count = 1;
+       int term_count = 0;
 
        while (1) {
                unsigned char translated[4];
                int count = 0;
 
+               /* Process one group of 4 chars */
                while (count < 4) {
                        char *table_ptr;
                        int ch;
 
                        /* Get next _valid_ character.
-                        * global vector bb_uuenc_tbl_base64[] contains this string:
+                        * bb_uuenc_tbl_base64[] contains this string:
+                        *  0         1         2         3         4         5         6
+                        *  012345678901234567890123456789012345678901234567890123456789012345
                         * "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=\n"
                         */
                        do {
@@ -103,42 +106,38 @@ static void read_base64(FILE *src_stream, FILE *dst_stream)
                                        bb_error_msg_and_die("short file");
                                }
                                table_ptr = strchr(bb_uuenc_tbl_base64, ch);
-                       } while (table_ptr == NULL);
+                       } while (!table_ptr);
 
                        /* Convert encoded character to decimal */
                        ch = table_ptr - bb_uuenc_tbl_base64;
 
-                       if (*table_ptr == '=') {
-                               if (term_count == 0) {
-                                       translated[count] = '\0';
-                                       break;
-                               }
-                               term_count++;
-                       } else if (*table_ptr == '\n') {
-                               /* Check for terminating line */
-                               if (term_count == 5) {
-                                       return;
-                               }
-                               term_count = 1;
-                               continue;
-                       } else {
-                               translated[count] = ch;
-                               count++;
+                       if (ch == 65 /* '\n' */) {
+                               /* Terminating "====" line? */
+                               if (term_count == 4)
+                                       return; /* yes */
                                term_count = 0;
+                               continue;
+                       }
+                       /* ch is 64 is char was '=', otherwise 0..63 */
+                       translated[count] = ch & 63; /* 64 -> 0 */
+                       if (ch == 64) {
+                               term_count++;
+                               break;
                        }
+                       count++;
                }
 
-               /* Merge 6 bit chars to 8 bit */
-               if (count > 1) {
+               /* Merge 6 bit chars to 8 bit.
+                * count can be < 4 when we decode the tail:
+                * "eQ==" -> "y", not "y NUL NUL"
+                */
+               if (count > 1)
                        fputc(translated[0] << 2 | translated[1] >> 4, dst_stream);
-               }
-               if (count > 2) {
+               if (count > 2)
                        fputc(translated[1] << 4 | translated[2] >> 2, dst_stream);
-               }
-               if (count > 3) {
+               if (count > 3)
                        fputc(translated[2] << 6 | translated[3], dst_stream);
-               }
-       }
+       } /* while (1) */
 }
 
 #if ENABLE_UUDECODE