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authorSiddhesh Poyarekar <siddhesh@redhat.com>2014-05-27 13:54:19 +0530
committerSiddhesh Poyarekar <siddhesh@redhat.com>2014-05-27 13:54:19 +0530
commit2482ae433a4249495859343ae1fba408300f2c2e (patch)
tree9fdaad4e75acb1672022be1c49862ee726134bd9 /libio/Makefile
parentbab900166e8b5f0f4081c5cf1afa0cd33b123714 (diff)
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Fix offset computation for append+ mode on switching from read (BZ #16724)
The offset computation in write mode uses the fact that _IO_read_end
is kept in sync with the external file offset.  This however is not
true when O_APPEND is in effect since switching to write mode ought to
send the external file offset to the end of file without making the
necessary adjustment to _IO_read_end.

Hence in append mode, offset computation when writing should only
consider the effect of unflushed writes, i.e. from _IO_write_base to
_IO_write_ptr.

The wiki has a detailed document that describes the rationale for
offsets returned by ftell in various conditions:

https://sourceware.org/glibc/wiki/File%20offsets%20in%20a%20stdio%20stream%20and%20ftell
Diffstat (limited to 'libio/Makefile')
-rw-r--r--libio/Makefile4
1 files changed, 3 insertions, 1 deletions
diff --git a/libio/Makefile b/libio/Makefile
index cca03454fc..b324ccc519 100644
--- a/libio/Makefile
+++ b/libio/Makefile
@@ -60,7 +60,8 @@ tests = tst_swprintf tst_wprintf tst_swscanf tst_wscanf tst_getwc tst_putwc   \
 	tst-wmemstream1 tst-wmemstream2 \
 	bug-memstream1 bug-wmemstream1 \
 	tst-setvbuf1 tst-popen1 tst-fgetwc bug-wsetpos tst-fseek \
-	tst-fwrite-error tst-ftell-partial-wide tst-ftell-active-handler
+	tst-fwrite-error tst-ftell-partial-wide tst-ftell-active-handler \
+	tst-ftell-append
 ifeq (yes,$(build-shared))
 # Add test-fopenloc only if shared library is enabled since it depends on
 # shared localedata objects.
@@ -160,6 +161,7 @@ tst-fgetwc-ENV = LOCPATH=$(common-objpfx)localedata
 tst-fseek-ENV = LOCPATH=$(common-objpfx)localedata
 tst-ftell-partial-wide-ENV = LOCPATH=$(common-objpfx)localedata
 tst-ftell-active-handler-ENV = LOCPATH=$(common-objpfx)localedata
+tst-ftell-append-ENV = LOCPATH=$(common-objpfx)localedata
 
 generated += tst-fopenloc.mtrace tst-fopenloc.check