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libctf, archive: stop ctf_arc_bufopen triggering crazy unmaps

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The archive machinery mmap()s its archives when possible: so it arranges
to do appropriately-sized unmaps by recording the unmap length in the
ctfa_magic value and unmapping that.

This brilliant (horrible) trick works less well when ctf_arc_bufopen is
called with an existing buffer (which might be a readonly mapping).
ctf_arc_bufopen always returns a ctf_archive_t wrapper, so record in
there the necessity to not unmap anything when a bufopen'ed archive is
closed again.

libctf/
	* ctf-impl.h (struct ctf_archive_internal)
	<ctfi_unmap_on_close>: New.
	(ctf_new_archive_internal): Adjust.
	* ctf-archive.c (ctf_new_archive_internal): Likewise.
	Initialize ctfi_unmap_on_close.  Adjust error path.
	(ctf_arc_bufopen): Adjust ctf_new_archive_internal call
	(unmap_on_close is 0).
	(ctf_arc_close): Only unmap if ctfi_unmap_on_close.
	* ctf-open-bfd.c (ctf_fdopen): Adjust.
This commit is contained in:
Nick Alcock
2020-06-02 20:55:05 +01:00
parent 96e3ec2966
commit 601e455b75
4 changed files with 40 additions and 12 deletions
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4
libctf/ctf-open-bfd.c
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@ -230,7 +230,7 @@ ctf_fdopen (int fd, const char *filename, const char *target, int *errp)
fp->ctf_data_mmapped = data;
fp->ctf_data_mmapped_len = (size_t) st.st_size;
return ctf_new_archive_internal (0, NULL, fp, NULL, NULL, errp);
return ctf_new_archive_internal (0, 1, NULL, fp, NULL, NULL, errp);
}
if ((nbytes = ctf_pread (fd, &arc_magic, sizeof (arc_magic), 0)) <= 0)
@ -243,7 +243,7 @@ ctf_fdopen (int fd, const char *filename, const char *target, int *errp)
if ((arc = ctf_arc_open_internal (filename, errp)) == NULL)
return NULL; /* errno is set for us. */
return ctf_new_archive_internal (1, arc, NULL, NULL, NULL, errp);
return ctf_new_archive_internal (1, 1, arc, NULL, NULL, NULL, errp);
}
/* Attempt to open the file with BFD. We must dup the fd first, since bfd