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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.
This commit is contained in:
Bram Moolenaar
2022-10-21 11:25:30 +01:00
parent 63c84731c1
commit 5b2a3d77d3
4 changed files with 32 additions and 13 deletions
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26
src/blob.c
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@@ -199,24 +199,32 @@ read_blob(FILE *fd, typval_T *rettv, off_T offset, off_T size_arg)
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;