92 lines
2.4 KiB
C
92 lines
2.4 KiB
C
/* Profile PC and write result to FIFO.
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Copyright (C) 1999-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1999.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <fcntl.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <unistd.h>
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/* Nonzero if we are actually doing something. */
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static int active;
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/* The file descriptor of the FIFO. */
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static int fd;
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static void
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__attribute__ ((constructor))
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install (void)
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{
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/* See whether the environment variable `PCPROFILE_OUTPUT' is defined.
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If yes, it should name a FIFO. We open it and mark ourself as active. */
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const char *outfile = getenv ("PCPROFILE_OUTPUT");
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if (outfile != NULL && *outfile != '\0')
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{
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fd = open (outfile, O_RDWR | O_CREAT, 0666);
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if (fd != -1)
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{
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uint32_t word;
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active = 1;
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/* Write a magic word which tells the reader about the byte
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order and the size of the following entries. */
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word = 0xdeb00000 | sizeof (void *);
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if (TEMP_FAILURE_RETRY (write (fd, &word, 4)) != 4)
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{
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/* If even this fails we shouldn't try further. */
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close (fd);
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fd = -1;
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active = 0;
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}
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}
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}
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}
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static void
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__attribute__ ((destructor))
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uninstall (void)
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{
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if (active)
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close (fd);
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}
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void
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__cyg_profile_func_enter (void *this_fn, void *call_site)
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{
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void *buf[2];
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if (! active)
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return;
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/* Now write out the current position and that of the caller. We do
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this now, and don't cache the because we want real-time output. */
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buf[0] = this_fn;
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buf[1] = call_site;
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write (fd, buf, sizeof buf);
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}
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/* We don't handle entry and exit differently here. */
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strong_alias (__cyg_profile_func_enter, __cyg_profile_func_exit)
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