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author | Jim Meyering <jim@meyering.net> | 1992-10-31 20:42:48 +0000 |
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committer | Jim Meyering <jim@meyering.net> | 1992-10-31 20:42:48 +0000 |
commit | 14fd34b78818660e05806b6eda178e3f846c5c21 (patch) | |
tree | b40038aa2684b5cd95ae2d5fcef564bcf8e05cc3 /lib/ftruncate.c | |
download | coreutils-14fd34b78818660e05806b6eda178e3f846c5c21.tar.xz |
Initial revision
Diffstat (limited to 'lib/ftruncate.c')
-rw-r--r-- | lib/ftruncate.c | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/lib/ftruncate.c b/lib/ftruncate.c new file mode 100644 index 000000000..17d263d51 --- /dev/null +++ b/lib/ftruncate.c @@ -0,0 +1,72 @@ +/* ftruncate emulations that work on some System V's. + This file is in the public domain. */ + +#include <sys/types.h> +#include <fcntl.h> + +#ifdef F_CHSIZE +int +ftruncate (fd, length) + int fd; + off_t length; +{ + return fcntl (fd, F_CHSIZE, length); +} +#else +#ifdef F_FREESP +/* The following function was written by + kucharsk@Solbourne.com (William Kucharski) */ + +#include <sys/stat.h> +#include <errno.h> +#include <unistd.h> + +int +ftruncate (fd, length) + int fd; + off_t length; +{ + struct flock fl; + struct stat filebuf; + + if (fstat (fd, &filebuf) < 0) + return -1; + + if (filebuf.st_size < length) + { + /* Extend file length. */ + if (lseek (fd, (length - 1), SEEK_SET) < 0) + return -1; + + /* Write a "0" byte. */ + if (write (fd, "", 1) != 1) + return -1; + } + else + { + /* Truncate length. */ + fl.l_whence = 0; + fl.l_len = 0; + fl.l_start = length; + fl.l_type = F_WRLCK; /* Write lock on file space. */ + + /* This relies on the UNDOCUMENTED F_FREESP argument to + fcntl, which truncates the file so that it ends at the + position indicated by fl.l_start. + Will minor miracles never cease? */ + if (fcntl (fd, F_FREESP, &fl) < 0) + return -1; + } + + return 0; +} +#else +int +ftruncate (fd, length) + int fd; + off_t length; +{ + return chsize (fd, length); +} +#endif +#endif |