Mercurial > vim
changeset 30952:61558a67630a v9.0.0810
patch 9.0.0810: readblob() returns empty when trying to read too much
Commit: https://github.com/vim/vim/commit/5b2a3d77d320d76f12b1666938a9d58c2a848205
Author: Bram Moolenaar <Bram@vim.org>
Date: Fri Oct 21 11:25:30 2022 +0100
patch 9.0.0810: readblob() returns empty when trying to read too much
Problem: readblob() returns empty when trying to read too much.
Solution: Return what is available.
| author | Bram Moolenaar <Bram@vim.org> |
|---|---|
| date | Fri, 21 Oct 2022 12:30:05 +0200 |
| parents | f2dd117ca94c |
| children | e0b47ccd75a4 |
| files | runtime/doc/builtin.txt src/blob.c src/testdir/test_blob.vim src/version.c |
| diffstat | 4 files changed, 32 insertions(+), 13 deletions(-) [+] |
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--- a/runtime/doc/builtin.txt +++ b/runtime/doc/builtin.txt @@ -6866,8 +6866,10 @@ readblob({fname} [, {offset} [, {size}]] readblob('/dev/ttyS0', 0, 10) < When the file can't be opened an error message is given and the result is an empty |Blob|. - When trying to read bytes beyond the end of the file the - result is an empty blob. + When the offset is beyond the end of the file the result is an + empty blob. + When trying to read more bytes than are available the result + is truncated. Also see |readfile()| and |writefile()|.
--- a/src/blob.c +++ b/src/blob.c @@ -199,24 +199,32 @@ read_blob(FILE *fd, typval_T *rettv, off if (offset >= 0) { - if (size == -1) + // The size defaults to the whole file. If a size is given it is + // limited to not go past the end of the file. + if (size == -1 || (size > st.st_size - offset +#ifdef S_ISCHR + && !S_ISCHR(st.st_mode) +#endif + )) // size may become negative, checked below size = st.st_size - offset; whence = SEEK_SET; } else { - if (size == -1) + // limit the offset to not go before the start of the file + if (-offset > st.st_size +#ifdef S_ISCHR + && !S_ISCHR(st.st_mode) +#endif + ) + offset = -st.st_size; + // Size defaults to reading until the end of the file. + if (size == -1 || size > -offset) size = -offset; whence = SEEK_END; } - // Trying to read bytes that aren't there results in an empty blob, not an - // error. - if (size <= 0 || ( -#ifdef S_ISCHR - !S_ISCHR(st.st_mode) && -#endif - size > st.st_size)) + if (size <= 0) return OK; if (offset != 0 && vim_fseek(fd, offset, whence) != 0) return OK;
--- a/src/testdir/test_blob.vim +++ b/src/testdir/test_blob.vim @@ -499,10 +499,17 @@ func Test_blob_read_write() VAR br6 = readblob('Xblob', -3, 2) call assert_equal(b[-3 : -2], br6) + #" reading past end of file, empty result VAR br1e = readblob('Xblob', 10000) call assert_equal(0z, br1e) - VAR br2e = readblob('Xblob', -10000) - call assert_equal(0z, br2e) + + #" reading too much, result is truncated + VAR blong = readblob('Xblob', -1000) + call assert_equal(b, blong) + LET blong = readblob('Xblob', -10, 8) + call assert_equal(b, blong) + LET blong = readblob('Xblob', 0, 10) + call assert_equal(b, blong) call delete('Xblob') END