Simplify fseek/ftell.
Another step towards _FILE_OFFSET_BITS=64 support.
Bug: http://b/24807045
Change-Id: I00b83c81a7b108176c4d9437bc32611f73b7e967
diff --git a/libc/Android.mk b/libc/Android.mk
index 2609644..85a58e7 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -464,9 +464,7 @@
upstream-openbsd/lib/libc/stdio/fputws.c \
upstream-openbsd/lib/libc/stdio/freopen.c \
upstream-openbsd/lib/libc/stdio/fscanf.c \
- upstream-openbsd/lib/libc/stdio/fseek.c \
upstream-openbsd/lib/libc/stdio/fsetpos.c \
- upstream-openbsd/lib/libc/stdio/ftell.c \
upstream-openbsd/lib/libc/stdio/funopen.c \
upstream-openbsd/lib/libc/stdio/fvwrite.c \
upstream-openbsd/lib/libc/stdio/fwalk.c \
diff --git a/libc/include/stdio.h b/libc/include/stdio.h
index fd653d9..268db78 100644
--- a/libc/include/stdio.h
+++ b/libc/include/stdio.h
@@ -73,9 +73,9 @@
#define __SMBF 0x0080 /* _buf is from malloc */
#define __SAPP 0x0100 /* fdopen()ed in append mode */
#define __SSTR 0x0200 /* this is an sprintf/snprintf string */
-#define __SOPT 0x0400 /* do fseek() optimization */
-#define __SNPT 0x0800 /* do not do fseek() optimization */
-#define __SOFF 0x1000 /* set iff _offset is in fact correct */
+/* #define __SOPT 0x0400 --- historical (do fseek() optimization). */
+/* #define __SNPT 0x0800 --- historical (do not do fseek() optimization). */
+/* #define __SOFF 0x1000 --- historical (set iff _offset is in fact correct). */
#define __SMOD 0x2000 /* true => fgetln modified _p text */
#define __SALC 0x4000 /* allocate string space dynamically */
#define __SIGN 0x8000 /* ignore this file in _fwalk */
diff --git a/libc/stdio/local.h b/libc/stdio/local.h
index a15bddf..7188c74 100644
--- a/libc/stdio/local.h
+++ b/libc/stdio/local.h
@@ -92,7 +92,6 @@
/* Unix stdio files get aligned to block boundaries on fseek() */
int _blksize; /* stat.st_blksize (may be != _bf._size) */
- fpos_t _offset; /* current lseek offset */
};
/*
@@ -112,6 +111,10 @@
bool _caller_handles_locking;
};
+// TODO: remove remaining references to these obsolete flags.
+#define __SNPT 0
+#define __SOPT 0
+
#if defined(__cplusplus)
#define _EXT(fp) reinterpret_cast<__sfileext*>((fp)->_ext._base)
#else
diff --git a/libc/stdio/stdio.cpp b/libc/stdio/stdio.cpp
index 1ea3ef5..1066d7f 100644
--- a/libc/stdio/stdio.cpp
+++ b/libc/stdio/stdio.cpp
@@ -35,6 +35,7 @@
#include <errno.h>
#include <fcntl.h>
+#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <sys/param.h>
@@ -51,7 +52,7 @@
#define std(flags, file) \
{0,0,0,flags,file,{0,0},0,__sF+file,__sclose,__sread,__sseek,__swrite, \
- {(unsigned char *)(__sFext+file), 0},NULL,0,{0},{0},{0,0},0,0}
+ {(unsigned char *)(__sFext+file), 0},NULL,0,{0},{0},{0,0},0}
_THREAD_PRIVATE_MUTEX(__sfp_mutex);
@@ -85,25 +86,38 @@
struct glue __sglue = { NULL, 3, __sF };
static struct glue* lastglue = &__sglue;
+class ScopedFileLock {
+ public:
+ ScopedFileLock(FILE* fp) : fp_(fp) {
+ FLOCKFILE(fp_);
+ }
+ ~ScopedFileLock() {
+ FUNLOCKFILE(fp_);
+ }
+
+ private:
+ FILE* fp_;
+};
+
static glue* moreglue(int n) {
- static FILE empty;
+ static FILE empty;
- char* data = new char[sizeof(glue) + ALIGNBYTES + n * sizeof(FILE) + n * sizeof(__sfileext)];
- if (data == nullptr) return nullptr;
+ char* data = new char[sizeof(glue) + ALIGNBYTES + n * sizeof(FILE) + n * sizeof(__sfileext)];
+ if (data == nullptr) return nullptr;
- glue* g = reinterpret_cast<glue*>(data);
- FILE* p = reinterpret_cast<FILE*>(ALIGN(data + sizeof(*g)));
- __sfileext* pext = reinterpret_cast<__sfileext*>(ALIGN(data + sizeof(*g)) + n * sizeof(FILE));
- g->next = NULL;
- g->niobs = n;
- g->iobs = p;
- while (--n >= 0) {
- *p = empty;
- _FILEEXT_SETUP(p, pext);
- p++;
- pext++;
- }
- return g;
+ glue* g = reinterpret_cast<glue*>(data);
+ FILE* p = reinterpret_cast<FILE*>(ALIGN(data + sizeof(*g)));
+ __sfileext* pext = reinterpret_cast<__sfileext*>(ALIGN(data + sizeof(*g)) + n * sizeof(FILE));
+ g->next = NULL;
+ g->niobs = n;
+ g->iobs = p;
+ while (--n >= 0) {
+ *p = empty;
+ _FILEEXT_SETUP(p, pext);
+ p++;
+ pext++;
+ }
+ return g;
}
/*
@@ -147,81 +161,155 @@
}
extern "C" __LIBC_HIDDEN__ void __libc_stdio_cleanup(void) {
- /* (void) _fwalk(fclose); */
- (void) _fwalk(__sflush); /* `cheating' */
+ // Equivalent to fflush(nullptr), but without all the locking since we're shutting down anyway.
+ _fwalk(__sflush);
}
int fclose(FILE* fp) {
- if (fp->_flags == 0) {
- // Already freed!
- errno = EBADF;
- return EOF;
- }
+ if (fp->_flags == 0) {
+ // Already freed!
+ errno = EBADF;
+ return EOF;
+ }
- FLOCKFILE(fp);
- WCIO_FREE(fp);
- int r = fp->_flags & __SWR ? __sflush(fp) : 0;
- if (fp->_close != NULL && (*fp->_close)(fp->_cookie) < 0) {
- r = EOF;
- }
- if (fp->_flags & __SMBF) free(fp->_bf._base);
- if (HASUB(fp)) FREEUB(fp);
- if (HASLB(fp)) FREELB(fp);
+ ScopedFileLock sfl(fp);
+ WCIO_FREE(fp);
+ int r = fp->_flags & __SWR ? __sflush(fp) : 0;
+ if (fp->_close != NULL && (*fp->_close)(fp->_cookie) < 0) {
+ r = EOF;
+ }
+ if (fp->_flags & __SMBF) free(fp->_bf._base);
+ if (HASUB(fp)) FREEUB(fp);
+ if (HASLB(fp)) FREELB(fp);
- // Poison this FILE so accesses after fclose will be obvious.
- fp->_file = -1;
- fp->_r = fp->_w = 0;
+ // Poison this FILE so accesses after fclose will be obvious.
+ fp->_file = -1;
+ fp->_r = fp->_w = 0;
- // Release this FILE for reuse.
- fp->_flags = 0;
- FUNLOCKFILE(fp);
- return (r);
+ // Release this FILE for reuse.
+ fp->_flags = 0;
+ return r;
}
int fileno(FILE* fp) {
- FLOCKFILE(fp);
- int result = fileno_unlocked(fp);
- FUNLOCKFILE(fp);
- return result;
+ ScopedFileLock sfl(fp);
+ return fileno_unlocked(fp);
}
-// Small standard I/O/seek/close functions.
-// These maintain the `known seek offset' for seek optimisation.
int __sread(void* cookie, char* buf, int n) {
- FILE* fp = reinterpret_cast<FILE*>(cookie);
- int ret = TEMP_FAILURE_RETRY(read(fp->_file, buf, n));
- // If the read succeeded, update the current offset.
- if (ret >= 0) {
- fp->_offset += ret;
- } else {
- fp->_flags &= ~__SOFF; // Paranoia.
- }
- return ret;
+ FILE* fp = reinterpret_cast<FILE*>(cookie);
+ return TEMP_FAILURE_RETRY(read(fp->_file, buf, n));
}
int __swrite(void* cookie, const char* buf, int n) {
- FILE* fp = reinterpret_cast<FILE*>(cookie);
- if (fp->_flags & __SAPP) {
- (void) TEMP_FAILURE_RETRY(lseek(fp->_file, 0, SEEK_END));
- }
- fp->_flags &= ~__SOFF; // In case FAPPEND mode is set.
- return TEMP_FAILURE_RETRY(write(fp->_file, buf, n));
+ FILE* fp = reinterpret_cast<FILE*>(cookie);
+ if (fp->_flags & __SAPP) {
+ // The FILE* is in append mode, but the underlying fd doesn't have O_APPEND set.
+ // We need to seek manually.
+ // TODO: can we use fcntl(2) to set O_APPEND in fdopen(3) instead?
+ TEMP_FAILURE_RETRY(lseek64(fp->_file, 0, SEEK_END));
+ }
+ return TEMP_FAILURE_RETRY(write(fp->_file, buf, n));
}
// TODO: _FILE_OFFSET_BITS=64.
fpos_t __sseek(void* cookie, fpos_t offset, int whence) {
- FILE* fp = reinterpret_cast<FILE*>(cookie);
- off_t ret = TEMP_FAILURE_RETRY(lseek(fp->_file, offset, whence));
- if (ret == -1) {
- fp->_flags &= ~__SOFF;
- } else {
- fp->_flags |= __SOFF;
- fp->_offset = ret;
- }
- return ret;
+ FILE* fp = reinterpret_cast<FILE*>(cookie);
+ return TEMP_FAILURE_RETRY(lseek(fp->_file, offset, whence));
}
int __sclose(void* cookie) {
- FILE* fp = reinterpret_cast<FILE*>(cookie);
- return close(fp->_file);
+ FILE* fp = reinterpret_cast<FILE*>(cookie);
+ return close(fp->_file);
+}
+
+static bool __file_is_seekable(FILE* fp) {
+ if (fp->_seek == nullptr) {
+ errno = ESPIPE; // Historic practice.
+ return false;
+ }
+ return true;
+}
+
+// TODO: _FILE_OFFSET_BITS=64.
+static off_t __ftello_unlocked(FILE* fp) {
+ if (!__file_is_seekable(fp)) return -1;
+
+ // Find offset of underlying I/O object, then
+ // adjust for buffered bytes.
+ __sflush(fp); // May adjust seek offset on append stream.
+ fpos_t result = (*fp->_seek)(fp->_cookie, 0, SEEK_CUR);
+ if (result == -1) {
+ return -1;
+ }
+
+ if (fp->_flags & __SRD) {
+ // Reading. Any unread characters (including
+ // those from ungetc) cause the position to be
+ // smaller than that in the underlying object.
+ result -= fp->_r;
+ if (HASUB(fp)) result -= fp->_ur;
+ } else if (fp->_flags & __SWR && fp->_p != NULL) {
+ // Writing. Any buffered characters cause the
+ // position to be greater than that in the
+ // underlying object.
+ result += fp->_p - fp->_bf._base;
+ }
+ return result;
+}
+
+int fseeko(FILE* fp, off_t offset, int whence) {
+ ScopedFileLock sfl(fp);
+
+ if (!__file_is_seekable(fp)) return -1;
+
+ // Change any SEEK_CUR to SEEK_SET, and check `whence' argument.
+ // After this, whence is either SEEK_SET or SEEK_END.
+ if (whence == SEEK_CUR) {
+ fpos_t current_offset = __ftello_unlocked(fp);
+ if (current_offset == -1) {
+ return EOF;
+ }
+ offset += current_offset;
+ whence = SEEK_SET;
+ } else if (whence != SEEK_SET && whence != SEEK_END) {
+ errno = EINVAL;
+ return EOF;
+ }
+
+ if (fp->_bf._base == NULL) __smakebuf(fp);
+
+ // Flush unwritten data and attempt the seek.
+ if (__sflush(fp) || (*fp->_seek)(fp->_cookie, offset, whence) == -1) {
+ return EOF;
+ }
+
+ // Success: clear EOF indicator and discard ungetc() data.
+ if (HASUB(fp)) FREEUB(fp);
+ fp->_p = fp->_bf._base;
+ fp->_r = 0;
+ /* fp->_w = 0; */ /* unnecessary (I think...) */
+ fp->_flags &= ~__SEOF;
+ return 0;
+}
+
+// TODO: _FILE_OFFSET_BITS=64.
+int fseek(FILE* fp, long offset, int whence) {
+ return fseeko(fp, offset, whence);
+}
+
+// TODO: _FILE_OFFSET_BITS=64.
+off_t ftello(FILE* fp) {
+ ScopedFileLock sfl(fp);
+ return __ftello_unlocked(fp);
+}
+
+// TODO: _FILE_OFFSET_BITS=64
+long ftell(FILE* fp) {
+ off_t offset = ftello(fp);
+ if (offset > LONG_MAX) {
+ errno = EOVERFLOW;
+ return -1;
+ }
+ return offset;
}
diff --git a/libc/upstream-openbsd/lib/libc/stdio/fseek.c b/libc/upstream-openbsd/lib/libc/stdio/fseek.c
deleted file mode 100644
index cdd40b6..0000000
--- a/libc/upstream-openbsd/lib/libc/stdio/fseek.c
+++ /dev/null
@@ -1,251 +0,0 @@
-/* $OpenBSD: fseek.c,v 1.11 2012/05/21 22:24:19 matthew Exp $ */
-/*-
- * Copyright (c) 1990, 1993
- * The Regents of the University of California. All rights reserved.
- *
- * This code is derived from software contributed to Berkeley by
- * Chris Torek.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- * may be used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <errno.h>
-#include "local.h"
-
-#define POS_ERR (-(fpos_t)1)
-
-/*
- * Seek the given file to the given offset.
- * `Whence' must be one of the three SEEK_* macros.
- */
-int
-fseeko(FILE *fp, off_t offset, int whence)
-{
- fpos_t (*seekfn)(void *, fpos_t, int);
- fpos_t target, curoff;
- size_t n;
- struct stat st;
- int havepos;
-
- /* make sure stdio is set up */
- if (!__sdidinit)
- __sinit();
-
- /*
- * Have to be able to seek.
- */
- if ((seekfn = fp->_seek) == NULL) {
- errno = ESPIPE; /* historic practice */
- return (EOF);
- }
-
- /*
- * Change any SEEK_CUR to SEEK_SET, and check `whence' argument.
- * After this, whence is either SEEK_SET or SEEK_END.
- */
- FLOCKFILE(fp);
- switch (whence) {
-
- case SEEK_CUR:
- /*
- * In order to seek relative to the current stream offset,
- * we have to first find the current stream offset a la
- * ftell (see ftell for details).
- */
- __sflush(fp); /* may adjust seek offset on append stream */
- if (fp->_flags & __SOFF)
- curoff = fp->_offset;
- else {
- curoff = (*seekfn)(fp->_cookie, (fpos_t)0, SEEK_CUR);
- if (curoff == (fpos_t)-1) {
- FUNLOCKFILE(fp);
- return (EOF);
- }
- }
- if (fp->_flags & __SRD) {
- curoff -= fp->_r;
- if (HASUB(fp))
- curoff -= fp->_ur;
- } else if (fp->_flags & __SWR && fp->_p != NULL)
- curoff += fp->_p - fp->_bf._base;
-
- offset += curoff;
- whence = SEEK_SET;
- havepos = 1;
- break;
-
- case SEEK_SET:
- case SEEK_END:
- curoff = 0; /* XXX just to keep gcc quiet */
- havepos = 0;
- break;
-
- default:
- FUNLOCKFILE(fp);
- errno = EINVAL;
- return (EOF);
- }
-
- /*
- * Can only optimise if:
- * reading (and not reading-and-writing);
- * not unbuffered; and
- * this is a `regular' Unix file (and hence seekfn==__sseek).
- * We must check __NBF first, because it is possible to have __NBF
- * and __SOPT both set.
- */
- if (fp->_bf._base == NULL)
- __smakebuf(fp);
- if (fp->_flags & (__SWR | __SRW | __SNBF | __SNPT))
- goto dumb;
- if ((fp->_flags & __SOPT) == 0) {
- if (seekfn != __sseek ||
- fp->_file < 0 || fstat(fp->_file, &st) ||
- (st.st_mode & S_IFMT) != S_IFREG) {
- fp->_flags |= __SNPT;
- goto dumb;
- }
- fp->_blksize = st.st_blksize;
- fp->_flags |= __SOPT;
- }
-
- /*
- * We are reading; we can try to optimise.
- * Figure out where we are going and where we are now.
- */
- if (whence == SEEK_SET)
- target = offset;
- else {
- if (fstat(fp->_file, &st))
- goto dumb;
- target = st.st_size + offset;
- }
-
- if (!havepos) {
- if (fp->_flags & __SOFF)
- curoff = fp->_offset;
- else {
- curoff = (*seekfn)(fp->_cookie, (fpos_t)0, SEEK_CUR);
- if (curoff == POS_ERR)
- goto dumb;
- }
- curoff -= fp->_r;
- if (HASUB(fp))
- curoff -= fp->_ur;
- }
-
- /*
- * Compute the number of bytes in the input buffer (pretending
- * that any ungetc() input has been discarded). Adjust current
- * offset backwards by this count so that it represents the
- * file offset for the first byte in the current input buffer.
- */
- if (HASUB(fp)) {
- curoff += fp->_r; /* kill off ungetc */
- n = fp->_up - fp->_bf._base;
- curoff -= n;
- n += fp->_ur;
- } else {
- n = fp->_p - fp->_bf._base;
- curoff -= n;
- n += fp->_r;
- }
-
- /*
- * If the target offset is within the current buffer,
- * simply adjust the pointers, clear EOF, undo ungetc(),
- * and return. (If the buffer was modified, we have to
- * skip this; see fgetln.c.)
- */
- if ((fp->_flags & __SMOD) == 0 &&
- target >= curoff && target < curoff + n) {
- int o = target - curoff;
-
- fp->_p = fp->_bf._base + o;
- fp->_r = n - o;
- if (HASUB(fp))
- FREEUB(fp);
- fp->_flags &= ~__SEOF;
- FUNLOCKFILE(fp);
- return (0);
- }
-
- /*
- * The place we want to get to is not within the current buffer,
- * but we can still be kind to the kernel copyout mechanism.
- * By aligning the file offset to a block boundary, we can let
- * the kernel use the VM hardware to map pages instead of
- * copying bytes laboriously. Using a block boundary also
- * ensures that we only read one block, rather than two.
- */
- curoff = target & ~(fp->_blksize - 1);
- if ((*seekfn)(fp->_cookie, curoff, SEEK_SET) == POS_ERR)
- goto dumb;
- fp->_r = 0;
- fp->_p = fp->_bf._base;
- if (HASUB(fp))
- FREEUB(fp);
- fp->_flags &= ~__SEOF;
- n = target - curoff;
- if (n) {
- if (__srefill(fp) || fp->_r < n)
- goto dumb;
- fp->_p += n;
- fp->_r -= n;
- }
- FUNLOCKFILE(fp);
- return (0);
-
- /*
- * We get here if we cannot optimise the seek ... just
- * do it. Allow the seek function to change fp->_bf._base.
- */
-dumb:
- if (__sflush(fp) ||
- (*seekfn)(fp->_cookie, (fpos_t)offset, whence) == POS_ERR) {
- FUNLOCKFILE(fp);
- return (EOF);
- }
- /* success: clear EOF indicator and discard ungetc() data */
- if (HASUB(fp))
- FREEUB(fp);
- fp->_p = fp->_bf._base;
- fp->_r = 0;
- /* fp->_w = 0; */ /* unnecessary (I think...) */
- fp->_flags &= ~__SEOF;
- FUNLOCKFILE(fp);
- return (0);
-}
-
-int
-fseek(FILE *fp, long offset, int whence)
-{
- return (fseeko(fp, offset, whence));
-}
diff --git a/libc/upstream-openbsd/lib/libc/stdio/ftell.c b/libc/upstream-openbsd/lib/libc/stdio/ftell.c
deleted file mode 100644
index 0a2016c..0000000
--- a/libc/upstream-openbsd/lib/libc/stdio/ftell.c
+++ /dev/null
@@ -1,96 +0,0 @@
-/* $OpenBSD: ftell.c,v 1.10 2012/05/21 22:24:19 matthew Exp $ */
-/*-
- * Copyright (c) 1990, 1993
- * The Regents of the University of California. All rights reserved.
- *
- * This code is derived from software contributed to Berkeley by
- * Chris Torek.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- * may be used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#include <stdio.h>
-#include <errno.h>
-#include <limits.h>
-#include "local.h"
-
-/*
- * ftello: return current offset.
- */
-off_t
-ftello(FILE *fp)
-{
- fpos_t pos;
-
- if (fp->_seek == NULL) {
- errno = ESPIPE; /* historic practice */
- pos = -1;
- goto out;
- }
-
- /*
- * Find offset of underlying I/O object, then
- * adjust for buffered bytes.
- */
- FLOCKFILE(fp);
- __sflush(fp); /* may adjust seek offset on append stream */
- if (fp->_flags & __SOFF)
- pos = fp->_offset;
- else {
- pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR);
- if (pos == -1)
- goto out;
- }
- if (fp->_flags & __SRD) {
- /*
- * Reading. Any unread characters (including
- * those from ungetc) cause the position to be
- * smaller than that in the underlying object.
- */
- pos -= fp->_r;
- if (HASUB(fp))
- pos -= fp->_ur;
- } else if (fp->_flags & __SWR && fp->_p != NULL) {
- /*
- * Writing. Any buffered characters cause the
- * position to be greater than that in the
- * underlying object.
- */
- pos += fp->_p - fp->_bf._base;
- }
-out: FUNLOCKFILE(fp);
- return (pos);
-}
-
-long
-ftell(FILE *fp)
-{
- off_t offset = ftello(fp);
- if (offset > LONG_MAX) {
- errno = EOVERFLOW;
- return (-1);
- }
- return ((long)offset);
-}
diff --git a/tests/stdio_test.cpp b/tests/stdio_test.cpp
index d054bf5..31acfec 100644
--- a/tests/stdio_test.cpp
+++ b/tests/stdio_test.cpp
@@ -1068,3 +1068,28 @@
ASSERT_EQ(-1, fileno(stdin));
ASSERT_EQ(EBADF, errno);
}
+
+TEST(STDIO_TEST, fseek_ftell_unseekable) {
+#if defined(__BIONIC__) // glibc has fopencookie instead.
+ auto read_fn = [](void*, char*, int) { return -1; };
+ FILE* fp = funopen(nullptr, read_fn, nullptr, nullptr, nullptr);
+ ASSERT_TRUE(fp != nullptr);
+
+ // Check that ftell balks on an unseekable FILE*.
+ errno = 0;
+ ASSERT_EQ(-1, ftell(fp));
+ ASSERT_EQ(ESPIPE, errno);
+
+ // SEEK_CUR is rewritten as SEEK_SET internally...
+ errno = 0;
+ ASSERT_EQ(-1, fseek(fp, 0, SEEK_CUR));
+ ASSERT_EQ(ESPIPE, errno);
+
+ // ...so it's worth testing the direct seek path too.
+ errno = 0;
+ ASSERT_EQ(-1, fseek(fp, 0, SEEK_SET));
+ ASSERT_EQ(ESPIPE, errno);
+
+ fclose(fp);
+#endif
+}
