9180c6045
Denys Vlasenko
2011-05-04
Subject
tar: store negative mtime as 0; pack very large files using base-256 encoding
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Architecture & Compiler Flags
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Commit Diff GitHub →
archival/tar.c+32 -4
| @@ -264,7 +264,8 @@ static int writeTarHeader(struct TarBallInfo *tbInfo, | |
| PUT_OCTAL(header.uid, statbuf->st_uid); | |
| PUT_OCTAL(header.gid, statbuf->st_gid); | |
| memset(header.size, '0', sizeof(header.size)-1); /* Regular file size is handled later */ | |
| - | PUT_OCTAL(header.mtime, statbuf->st_mtime); |
| + | /* users report that files with negative st_mtime cause trouble, so: */ |
| + | PUT_OCTAL(header.mtime, statbuf->st_mtime >= 0 ? statbuf->st_mtime : 0); |
| /* Enter the user and group names */ | |
| safe_strncpy(header.uname, get_cached_username(statbuf->st_uid), sizeof(header.uname)); | |
| @@ -316,15 +317,42 @@ static int writeTarHeader(struct TarBallInfo *tbInfo, | |
| } else if (S_ISFIFO(statbuf->st_mode)) { | |
| header.typeflag = FIFOTYPE; | |
| } else if (S_ISREG(statbuf->st_mode)) { | |
| - | if (sizeof(statbuf->st_size) > 4 |
| - | && statbuf->st_size > (off_t)0777777777777LL |
| + | /* header.size field is 12 bytes long */ |
| + | /* Does octal-encoded size fit? */ |
| + | uoff_t filesize = statbuf->st_size; |
| + | if (sizeof(filesize) <= 4 |
| + | || filesize <= (uoff_t)0777777777777LL |
| ) { | |
| + | PUT_OCTAL(header.size, filesize); |
| + | } |
| + | /* Does base256-encoded size fit? |
| + | * It always does unless off_t is wider than 64 bits. |
| + | */ |
| + | else if (ENABLE_FEATURE_TAR_GNU_EXTENSIONS |
| + | #if ULLONG_MAX > 0xffffffffffffffffLL /* 2^64-1 */ |
| + | && (filesize <= 0x3fffffffffffffffffffffffLL) |
| + | #endif |
| + | ) { |
| + | /* GNU tar uses "base-256 encoding" for very large numbers. |
| + | * Encoding is binary, with highest bit always set as a marker |
| + | * and sign in next-highest bit: |
| + | * 80 00 .. 00 - zero |
| + | * bf ff .. ff - largest positive number |
| + | * ff ff .. ff - minus 1 |
| + | * c0 00 .. 00 - smallest negative number |
| + | */ |
| + | char *p8 = header.size + sizeof(header.size); |
| + | do { |
| + | *--p8 = (uint8_t)filesize; |
| + | filesize >>= 8; |
| + | } while (p8 != header.size); |
| + | *p8 |= 0x80; |
| + | } else { |
| bb_error_msg_and_die("can't store file '%s' " | |
| "of size %"OFF_FMT"u, aborting", | |
| fileName, statbuf->st_size); | |
| } | |
| header.typeflag = REGTYPE; | |
| - | PUT_OCTAL(header.size, statbuf->st_size); |
| } else { | |
| bb_error_msg("%s: unknown file type", fileName); | |
| return FALSE; | |
include/archive.h+1 -1
| @@ -125,7 +125,7 @@ typedef struct archive_handle_t { | |
| #define TAR_BLOCK_SIZE 512 | |
| #define NAME_SIZE 100 | |
| #define NAME_SIZE_STR "100" | |
| - | typedef struct tar_header_t { /* byte offset */ |
| + | typedef struct tar_header_t { /* byte offset */ |
| char name[NAME_SIZE]; /* 0-99 */ | |
| char mode[8]; /* 100-107 */ | |
| char uid[8]; /* 108-115 */ | |