diff --git a/src/system.c b/src/system.c index ba4ac2d..ea88cd6 100644 --- a/src/system.c +++ b/src/system.c @@ -231,8 +231,25 @@ sys_compare_links (struct stat *link_data, struct stat *stat_data) int sys_truncate (int fd) { + struct stat st; off_t pos = lseek (fd, (off_t) 0, SEEK_CUR); - return pos < 0 ? -1 : ftruncate (fd, pos); + + if ( pos < 0) + return -1; + + if ( ftruncate(fd, pos) && errno == EPERM ) { + /* wrapper around ftruncate: + * ftruncate may fail to grow the size of a file with some OS and filesystem + * combinations. Linux and vfat/fat is one example. If this is the case do + * a write to grow the file to the desired length. + */ + if( (fstat( fd, &st ) == -1) || + (st.st_size >= pos) || + (lseek( fd, pos - 1, SEEK_SET) == (off_t)-1) || + (write( fd, "\0", 1) == -1) ) + return -1; + } + return 0; } /* Return nonzero if NAME is the name of a regular file, or if the file