[PATCH] Add av_file_map() and av_file_unmap() functions.

Stefano Sabatini stefano.sabatini-lala
Fri Nov 26 01:27:58 CET 2010


---
 configure          |    2 +
 libavutil/Makefile |    2 +
 libavutil/file.c   |  106 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 libavutil/file.h   |   57 ++++++++++++++++++++++++++++
 4 files changed, 167 insertions(+), 0 deletions(-)
 create mode 100644 libavutil/file.c
 create mode 100644 libavutil/file.h

diff --git a/configure b/configure
index 8f7cf12..02a89c7 100755
--- a/configure
+++ b/configure
@@ -1041,6 +1041,7 @@ HAVE_LIST="
     malloc_h
     memalign
     mkstemp
+    mmap
     pld
     posix_memalign
     round
@@ -2670,6 +2671,7 @@ check_func  inet_aton $network_extralibs
 check_func  isatty
 check_func  ${malloc_prefix}memalign            && enable memalign
 check_func  mkstemp
+check_func  mmap
 check_func  ${malloc_prefix}posix_memalign      && enable posix_memalign
 check_func  setrlimit
 check_func  strerror_r
diff --git a/libavutil/Makefile b/libavutil/Makefile
index e9ac965..fe0302c 100644
--- a/libavutil/Makefile
+++ b/libavutil/Makefile
@@ -15,6 +15,7 @@ HEADERS = adler32.h                                                     \
           error.h                                                       \
           eval.h                                                        \
           fifo.h                                                        \
+          file.h                                                        \
           intfloat_readwrite.h                                          \
           intreadwrite.h                                                \
           lfg.h                                                         \
@@ -42,6 +43,7 @@ OBJS = adler32.o                                                        \
        error.o                                                          \
        eval.o                                                           \
        fifo.o                                                           \
+       file.o                                                           \
        intfloat_readwrite.o                                             \
        inverse.o                                                        \
        lfg.o                                                            \
diff --git a/libavutil/file.c b/libavutil/file.c
new file mode 100644
index 0000000..6ca7a6b
--- /dev/null
+++ b/libavutil/file.c
@@ -0,0 +1,106 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "file.h"
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#if HAVE_MMAP
+#include <sys/mman.h>
+#endif
+
+int av_file_map(const char *filename, uint8_t **bufptr, size_t *size, int protect,
+                void *log_ctx)
+{
+    int protect2, fd = open(filename, O_RDONLY);
+    struct stat st;
+    void *ptr;
+    off_t off_size;
+
+    *bufptr = NULL;
+    if (fd < 0) {
+        av_log(log_ctx, AV_LOG_ERROR,
+               "Cannot read file '%s': %s\n", filename, strerror(errno));
+        return AVERROR(errno);
+    }
+
+    if (lstat(filename, &st) < 0) {
+        close(fd);
+        return AVERROR(errno);
+    }
+
+    off_size = st.st_size;
+    if (off_size > SIZE_MAX) {
+        av_log(log_ctx, AV_LOG_ERROR,
+               "File size for file '%s' is too big\n", filename);
+        close(fd);
+        return AVERROR(EINVAL);
+    }
+    *size = off_size;
+
+#if HAVE_MMAP
+    protect2 =  protect & AV_FILE_PROT_READ  ? PROT_READ : 0;
+    protect2 |= protect & AV_FILE_PROT_WRITE ? PROT_WRITE: 0;
+    protect2 |= protect & AV_FILE_PROT_EXEC  ? PROT_EXEC : 0;
+    ptr = mmap(NULL, *size, protect2, MAP_PRIVATE, fd, 0);
+    if ((int)(ptr) == -1) {
+        av_log(log_ctx, AV_LOG_ERROR, "Error occurred in mmap(): %s\n", strerror(errno));
+        close(fd);
+        return (int)ptr;
+    }
+    *bufptr = ptr;
+#else
+    *bufptr = av_malloc(*size);
+    if (!*bufptr) {
+        close(fd);
+        return AVERROR(ENOMEM);
+    }
+    read(fd, *bufptr, *size);
+#endif
+
+    return fd;
+}
+
+void av_file_unmap(int fd, uint8_t *bufptr, size_t size)
+{
+#if HAVE_MMAP
+    munmap(bufptr, size);
+#else
+    av_free(bufptr);
+#endif
+    close(fd);
+}
+
+#ifdef TEST
+
+#undef printf
+
+int main(void)
+{
+    uint8_t *buf;
+    size_t size;
+    int fd = av_file_map("file.c", &buf, &size, AV_FILE_PROT_READ|AV_FILE_PROT_WRITE, NULL);
+    if (fd < 0)
+        return 1;
+
+    buf[0] = 's';
+    printf("%s", buf);
+    av_file_unmap(fd, buf, size);
+    return 0;
+}
+#endif
diff --git a/libavutil/file.h b/libavutil/file.h
new file mode 100644
index 0000000..b599d94
--- /dev/null
+++ b/libavutil/file.h
@@ -0,0 +1,57 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVUTIL_FILE_H
+#define AVUTIL_FILE_H
+
+#include "avutil.h"
+
+/**
+ * @file misc file utilities
+ */
+
+#define AV_FILE_PROT_READ  1
+#define AV_FILE_PROT_WRITE 2
+#define AV_FILE_PROT_EXEC  4
+
+/**
+ * Read the file with name filename, and put its content in a newly
+ * allocated buffer or map it with mmap() when available. If filename
+ * references a link, the content of the linked file is read.
+ *
+ * @param bufptr pointer where the pointer to the file buffer is
+ * returned, *bufptr can be an allocated buffer or accessed through
+ * mmaplocation, is set to NULL in case of failure
+ * @param size pointer where the size of the file buffer is returned
+ * @param protect flags that control what kind of access is permitted,
+ * it can be any combination of the AV_FILE_PROT* flags, it is ignored
+ * if mmap() is not available
+ * @param log_ctx context used for logging
+ * @return the file descriptor in case of success, a negative value
+ * corresponding to an AVERROR error code in case of failure
+ */
+int av_file_map(const char *filename, uint8_t **bufptr, size_t *size, int protect,
+                void *log_ctx);
+
+/**
+ * Unmap the file with filedescriptor fd, and free the allocated or
+ * mmapped buffer in *bufptr with size size.
+ */
+void av_file_unmap(int fd, uint8_t *bufptr, size_t size);
+
+#endif /* AVUTIL_FILE_H */
-- 
1.7.2.3


--qDbXVdCdHGoSgWSk--



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