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authorJoseph Myers <joseph@codesourcery.com>2018-02-15 20:58:16 +0000
committerFangrui Song <maskray@google.com>2021-11-19 13:20:26 -0800
commitd7c1214f4d417119c4cca5c36c2adfc4d83be8fc (patch)
treea6adef5fb4201447a4c565d9989d2e0094919872
parentaac0d8a9a3a1ffbfd105de339c8653f39fc5ef17 (diff)
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Use libc_hidden_* for fputs (bug 15105).
Among other localplt test failures when building with -Os, there are libc.so PLT references for fputs. fputs calls normally get redirected to _IO_fputs by a macro in include/stdio.h (and _IO_fputs in turn uses libc_hidden_proto), but GCC can convert an fprintf call with a constant string argument into an fputs call, which of course is then unaffected by the macro redirection. (I don't know why this issue only appears with -Os.) This patch duly adds a use of libc_hidden_proto for fputs. I see no obvious reason why the fputs macro redirection is needed at all, but this patch does not change it. Tested for x86_64 (both that it removes this particular localplt failure for -Os - but other such failures remain so the bug can't yet be closed - and that the testsuite continues to pass without -Os). [BZ #15105] * include/stdio.h [!_ISOMAC && IS_IN (libc)] (fputs): Use libc_hidden_proto. * libio/iofputs.c (fputs): Use libc_hidden_weak. (cherry picked from commit 499b315324519f8deb5b42a143a76319934a3ab0)
-rw-r--r--include/stdio.h4
-rw-r--r--libio/iofputs.c1
2 files changed, 5 insertions, 0 deletions
diff --git a/include/stdio.h b/include/stdio.h
index f1e987a..6759ed3 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -135,6 +135,10 @@ extern int _IO_new_fclose (_IO_FILE*);
# define fclose(fp) _IO_new_fclose (fp)
extern int _IO_fputs (const char*, _IO_FILE*);
libc_hidden_proto (_IO_fputs)
+/* The compiler may optimize calls to fprintf into calls to fputs.
+ Use libc_hidden_proto to ensure that those calls, not redirected by
+ the fputs macro, also do not go through the PLT. */
+libc_hidden_proto (fputs)
# define fputs(str, fp) _IO_fputs (str, fp)
extern int _IO_new_fsetpos (_IO_FILE *, const _IO_fpos_t *);
# define fsetpos(fp, posp) _IO_new_fsetpos (fp, posp)
diff --git a/libio/iofputs.c b/libio/iofputs.c
index b4fbeb5..176e9ed 100644
--- a/libio/iofputs.c
+++ b/libio/iofputs.c
@@ -43,6 +43,7 @@ _IO_fputs (const char *str, _IO_FILE *fp)
libc_hidden_def (_IO_fputs)
weak_alias (_IO_fputs, fputs)
+libc_hidden_weak (fputs)
# ifndef _IO_MTSAFE_IO
strong_alias (_IO_fputs, __fputs_unlocked)