/* truncate.c - set file length, extending sparsely if necessary * * Copyright 2011 Rob Landley <rob@landley.net> USE_TRUNCATE(NEWTOY(truncate, "<1s:|c", TOYFLAG_USR|TOYFLAG_BIN)) config TRUNCATE bool "truncate" default y help usage: truncate [-c] -s SIZE file... Set length of file(s), extending sparsely if necessary. -c Don't create file if it doesn't exist -s New size (with optional prefix and suffix) SIZE prefix: + add, - subtract, < shrink to, > expand to, / multiple rounding down, % multiple rounding up SIZE suffix: k=1024, m=1024^2, g=1024^3, t=1024^4, p=1024^5, e=1024^6 */ #define FOR_truncate #include "toys.h" GLOBALS( char *s; long size; int type; ) static void do_truncate(int fd, char *name) { long long size; if (fd<0) return; if (TT.type == -1) size = TT.size; else { size = fdlength(fd); if (TT.type<2) size += TT.size*(1-(2*TT.type)); else if (TT.type<4) { if ((TT.type==2) ? (size <= TT.size) : (size >= TT.size)) return; size = TT.size; } else { size = (size+(TT.type-4)*(TT.size-1))/TT.size; size *= TT.size; } } if (ftruncate(fd, size)) perror_msg("'%s' to '%lld'", name, size); } void truncate_main(void) { int cr = !(toys.optflags&FLAG_c); if (-1 != (TT.type = stridx("+-<>/%", *TT.s))) TT.s++; TT.size = atolx(TT.s); // Create files with mask rwrwrw. // Nonexistent files are only an error if we're supposed to create them. loopfiles_rw(toys.optargs, O_WRONLY|O_CLOEXEC|(cr ? O_CREAT|WARN_ONLY : 0), 0666, do_truncate); }