uudecode,base64: code shrink

function                                             old     new   delta
read_base64                                          373     358     -15

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

1 files changed, 26 insertions, 27 deletions

diff --git a/coreutils/uudecode.c b/coreutils/uudecode.c
index 207fb0b8d..0da9b0988 100644
--- 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