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vim-patch:9.0.0810: readblob() returns empty when trying to read too much

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Problem:    readblob() returns empty when trying to read too much.
Solution:   Return what is available.

5b2a3d77d3

Co-authored-by: Bram Moolenaar <Bram@vim.org>
This commit is contained in:
zeertzjq
2023-02-28 19:29:59 +08:00
parent 4bd0611d7b
commit 7aad75e293
3 changed files with 24 additions and 10 deletions
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17
src/nvim/eval.c
View File

@@ -5879,22 +5879,27 @@ int read_blob(FILE *const fd, typval_T *rettv, off_T offset, off_T size_arg)
int whence;
off_T size = size_arg;
const off_T file_size = (off_T)os_fileinfo_size(&file_info);
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 > file_size - offset && !S_ISCHR(file_info.stat.st_mode))) {
// size may become negative, checked below
size = (off_T)os_fileinfo_size(&file_info) - offset;
}
whence = SEEK_SET;
} else {
if (size == -1) {
// limit the offset to not go before the start of the file
if (-offset > file_size && !S_ISCHR(file_info.stat.st_mode)) {
offset = -file_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 || (!S_ISCHR(file_info.stat.st_mode)
&& size > (off_T)os_fileinfo_size(&file_info))) {
if (size <= 0) {
return OK;
}
if (offset != 0 && vim_fseek(fd, offset, whence) != 0) {

11
src/nvim/testdir/test_blob.vim
View File

@@ -450,10 +450,17 @@ 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