From 805b08cf02f07c2b63f25890050042b518002bc3 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Sat, 19 Jun 1999 06:19:27 +0000 Subject: [PATCH] (to_oct): Prepend leading zeros, not spaces. Output a trailing NUL unless the value won't fit without it; this is backward compatible with Unix tar (and with GNU Emacs). (finish_header): No need to append NUL to chksum, now that to_oct is doing it. --- src/create.c | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-) diff --git a/src/create.c b/src/create.c index 0d7e67e..3a7e56a 100644 --- a/src/create.c +++ b/src/create.c @@ -65,9 +65,11 @@ struct link *linklist = NULL; /* points to first link in list */ | fact is used by start_header and finish_header, so don't change it! | `------------------------------------------------------------------------*/ -/* This should be equivalent to: sprintf (WHERE, "%*lo", SIZE, VALUE); - except that we don't assume VALUE fits in an unsigned long, and - except that sprintf fills in the trailing NUL and we don't. */ +/* Output VALUE in octal, using SUBSTITUTE if value won't fit. + Output to buffer WHERE with size SIZE. + TYPE is the kind of value being output (useful for diagnostics). + Prefer SIZE - 1 octal digits (with leading '0's), followed by '\0'; + but if SIZE octal digits would fit, omit the '\0'. */ static void to_oct (uintmax_t value, uintmax_t substitute, char *where, size_t size, const char *type) @@ -75,6 +77,15 @@ to_oct (uintmax_t value, uintmax_t substitute, char *where, size_t size, const c uintmax_t v = value; size_t i = size; +# define MAX_OCTAL_VAL_WITH_DIGITS(digits) \ + ((digits) * 3 < sizeof (uintmax_t) * CHAR_BIT \ + ? ((uintmax_t) 1 << ((digits) * 3)) - 1 \ + : (uintmax_t) -1) + + /* Output a trailing NUL unless the value is too large. */ + if (value <= MAX_OCTAL_VAL_WITH_DIGITS (size - 1)) + where[--i] = '\0'; + /* Produce the digits -- at least one. */ do @@ -84,16 +95,13 @@ to_oct (uintmax_t value, uintmax_t substitute, char *where, size_t size, const c } while (i != 0 && v != 0); - /* Leading spaces, if necessary. */ + /* Leading zeros, if necessary. */ while (i != 0) - where[--i] = ' '; + where[--i] = '0'; if (v != 0) { - int bits = size * 3; - uintmax_t maxval = (bits < sizeof (uintmax_t) * CHAR_BIT - ? ((uintmax_t) 1 << bits) - 1 - : (uintmax_t) -1); + uintmax_t maxval = MAX_OCTAL_VAL_WITH_DIGITS (size); char buf1[UINTMAX_STRSIZE_BOUND]; char buf2[UINTMAX_STRSIZE_BOUND]; char buf3[UINTMAX_STRSIZE_BOUND]; @@ -395,7 +403,7 @@ finish_header (union block *header) /* Fill in the checksum field. It's formatted differently from the other fields: it has [6] digits, a null, then a space -- rather than - digits, then a null. We use to_oct then write the null. + digits, then a null. We use to_oct. The final space is already there, from checksumming, and to_oct doesn't modify it. @@ -403,8 +411,7 @@ finish_header (union block *header) sprintf(header->header.chksum, "%6o", sum); */ - uintmax_to_oct ((uintmax_t) sum, header->header.chksum, 6); - header->header.chksum[6] = '\0'; + uintmax_to_oct ((uintmax_t) sum, header->header.chksum, 7); set_next_block_after (header); -- 2.44.0