Mercurial > hg > toybox
view toys/posix/cksum.c @ 1531:3ff823086c99 draft
Teach ln -f to leave original target alone if link creation fails.
Suggested by Ashwini Sharma, I wound up implementing it by creating the new
link at a temporary name and renaming it over the old one instead of renaming
the old file out of the way and putting it back if it failed.
(Because "mkdir -p one/one/blah && ln -sf /bin/one one" would otherwise
rename one/one out of the way and only notice it can't delete it way at the
end when recovery's darn awkward, vs create new thing and if rename fails
(including EISDIR) that's the main error path. And yes the temporary name
is in the same directory as the destination so we never rename between mounts.)
link over the old one instead of renaming the old file and renaming it back.
author | Rob Landley <rob@landley.net> |
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date | Wed, 22 Oct 2014 17:11:06 -0500 |
parents | 22739b6d5a0e |
children |
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/* cksum.c - produce crc32 checksum value for each input * * Copyright 2008 Rob Landley <rob@landley.net> * * See http://opengroup.org/onlinepubs/9699919799/utilities/cksum.html USE_CKSUM(NEWTOY(cksum, "HIPLN", TOYFLAG_BIN)) config CKSUM bool "cksum" default y help usage: cksum [-IPLN] [file...] For each file, output crc32 checksum value, length and name of file. If no files listed, copy from stdin. Filename "-" is a synonym for stdin. -H Hexadecimal checksum (defaults to decimal) -L Little endian (defaults to big endian) -P Pre-inversion -I Skip post-inversion -N Do not include length in CRC calculation */ #define FOR_cksum #include "toys.h" GLOBALS( unsigned crc_table[256]; ) static unsigned cksum_be(unsigned crc, unsigned char c) { return (crc<<8)^TT.crc_table[(crc>>24)^c]; } static unsigned cksum_le(unsigned crc, unsigned char c) { return TT.crc_table[(crc^c)&0xff] ^ (crc>>8); } static void do_cksum(int fd, char *name) { unsigned crc = (toys.optflags & FLAG_P) ? 0xffffffff : 0; uint64_t llen = 0, llen2; unsigned (*cksum)(unsigned crc, unsigned char c); cksum = (toys.optflags & FLAG_L) ? cksum_le : cksum_be; // CRC the data for (;;) { int len, i; len = read(fd, toybuf, sizeof(toybuf)); if (len<0) perror_msg("%s", name); if (len<1) break; llen += len; for (i=0; i<len; i++) crc=cksum(crc, toybuf[i]); } // CRC the length llen2 = llen; if (!(toys.optflags & FLAG_N)) { while (llen) { crc = cksum(crc, llen); llen >>= 8; } } printf((toys.optflags & FLAG_H) ? "%x" : "%u", (toys.optflags & FLAG_I) ? crc : ~crc); printf(" %"PRIu64, llen2); if (strcmp("-", name)) printf(" %s", name); xputc('\n'); } void cksum_main(void) { crc_init(TT.crc_table, toys.optflags & FLAG_L); loopfiles(toys.optargs, do_cksum); }