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wasi: implement file truncation

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The way this is implemented destroys the contents of the file, so
revisit if this causes issues in the future.
This commit is contained in:
Jacob Young 2022-11-30 01:26:25 -05:00 committed by Andrew Kelley
parent 1263346774
commit e000db2782
1 changed files with 11 additions and 4 deletions
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15
stage1/wasi.c
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@ -555,10 +555,17 @@ uint32_t wasi_snapshot_preview1_fd_filestat_set_size(uint32_t fd, uint64_t size)
if (fseek(fds[fd].stream, 0, SEEK_END) < 0) return wasi_errno_io;
long old_size = ftell(fds[fd].stream);
if (old_size < 0) return wasi_errno_io;
if (size > (unsigned long)old_size) {
if (fseek(fds[fd].stream, size - 1, SEEK_SET) < 0) return wasi_errno_io;
fputc(0, fds[fd].stream);
} else if (size < (unsigned long)old_size) panic("unimplemented");
if (size != (unsigned long)old_size) {
if (size > 0 && fseek(fds[fd].stream, size - 1, SEEK_SET) < 0) return wasi_errno_io;
if (size < (unsigned long)old_size) {
// Note that this destroys the contents on resize might have to save truncated
// file in memory if this becomes an issue.
FILE *trunc = fopen(des[fds[fd].de].host_path, "wb");
if (trunc == NULL) return wasi_errno_io;
fclose(trunc);
}
if (size > 0) fputc(0, fds[fd].stream);
}
if (fsetpos(fds[fd].stream, &pos) < 0) return wasi_errno_io;
return wasi_errno_success;
}