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diff --git a/lib/libarchive/archive_read.3 b/lib/libarchive/archive_read.3 new file mode 100644 index 0000000..1575c7b --- /dev/null +++ b/lib/libarchive/archive_read.3 @@ -0,0 +1,493 @@ +.\" Copyright (c) 2003-2005 Tim Kientzle +.\" All rights reserved. +.\" +.\" 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. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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. +.\" +.\" $FreeBSD$ +.\" +.Dd January 8, 2005 +.Dt archive_read 3 +.Os +.Sh NAME +.Nm archive_read_new , +.Nm archive_read_set_bytes_per_block , +.Nm archive_read_support_compression_all , +.Nm archive_read_support_compression_bzip2 , +.Nm archive_read_support_compression_compress , +.Nm archive_read_support_compression_gzip , +.Nm archive_read_support_compression_none , +.Nm archive_read_support_format_all , +.Nm archive_read_support_format_cpio , +.Nm archive_read_support_format_iso9660 , +.Nm archive_read_support_format_tar , +.Nm archive_read_support_format_zip , +.Nm archive_read_open , +.Nm archive_read_open_fd , +.Nm archive_read_open_file , +.Nm archive_read_next_header , +.Nm archive_read_data , +.Nm archive_read_data_block , +.Nm archive_read_data_skip , +.Nm archive_read_data_into_buffer , +.Nm archive_read_data_into_fd , +.Nm archive_read_extract , +.Nm archive_read_extract_set_progress_callback , +.Nm archive_read_close , +.Nm archive_read_finish +.Nd functions for reading streaming archives +.Sh SYNOPSIS +.In archive.h +.Ft struct archive * +.Fn archive_read_new "void" +.Ft int +.Fn archive_read_set_bytes_per_block "struct archive *" "int" +.Ft int +.Fn archive_read_support_compression_all "struct archive *" +.Ft int +.Fn archive_read_support_compression_bzip2 "struct archive *" +.Ft int +.Fn archive_read_support_compression_compress "struct archive *" +.Ft int +.Fn archive_read_support_compression_gzip "struct archive *" +.Ft int +.Fn archive_read_support_compression_none "struct archive *" +.Ft int +.Fn archive_read_support_format_all "struct archive *" +.Ft int +.Fn archive_read_support_format_cpio "struct archive *" +.Ft int +.Fn archive_read_support_format_iso9660 "struct archive *" +.Ft int +.Fn archive_read_support_format_tar "struct archive *" +.Ft int +.Fn archive_read_support_format_zip "struct archive *" +.Ft int +.Fn archive_read_open "struct archive *" "void *client_data" "archive_open_callback *" "archive_read_callback *" "archive_close_callback *" +.Ft int +.Fn archive_read_open_fd "struct archive *" "int fd" "size_t block_size" +.Ft int +.Fn archive_read_open_file "struct archive *" "const char *filename" "size_t block_size" +.Ft int +.Fn archive_read_next_header "struct archive *" "struct archive_entry **" +.Ft ssize_t +.Fn archive_read_data "struct archive *" "void *buff" "size_t len" +.Ft int +.Fn archive_read_data_block "struct archive *" "const void **buff" "size_t *len" "off_t *offset" +.Ft int +.Fn archive_read_data_skip "struct archive *" +.Ft int +.Fn archive_read_data_into_buffer "struct archive *" "void *" "ssize_t len" +.Ft int +.Fn archive_read_data_into_fd "struct archive *" "int fd" +.Ft int +.Fn archive_read_extract "struct archive *" "struct archive_entry *" "int flags" +.Ft void +.Fn archive_read_extract_set_progress_callback "struct archive *" "void (*func)(void *)" "void *user_data" +.Ft int +.Fn archive_read_close "struct archive *" +.Ft void +.Fn archive_read_finish "struct archive *" +.Sh DESCRIPTION +These functions provide a complete API for reading streaming archives. +The general process is to first create the +.Tn struct archive +object, set options, initialize the reader, iterate over the archive +headers and associated data, then close the archive and release all +resources. +The following summary describes the functions in approximately the +order they would be used: +.Bl -tag -compact -width indent +.It Fn archive_read_new +Allocates and initializes a +.Tn struct archive +object suitable for reading from an archive. +.It Fn archive_read_set_bytes_per_block +Sets the block size used for reading the archive data. +This controls the size that will be used when invoking the read +callback function. +The default is 20 records or 10240 bytes for tar formats. +.It Fn archive_read_support_compression_all , Fn archive_read_support_compression_bzip2 , Fn archive_read_support_compression_compress , Fn archive_read_support_compression_gzip , Fn archive_read_support_compression_none +Enables auto-detection code and decompression support for the +specified compression. +Note that +.Dq none +is always enabled by default. +For convenience, +.Fn archive_read_support_compression_all +enables all available decompression code. +.It Fn archive_read_support_format_all , Fn archive_read_support_format_cpio , Fn archive_read_support_format_iso9660 , Fn archive_read_support_format_tar, Fn archive_read_support_format_zip +Enables support---including auto-detection code---for the +specified archive format. +For example, +.Fn archive_read_support_format_tar +enables support for a variety of standard tar formats, old-style tar, +ustar, pax interchange format, and many common variants. +For convenience, +.Fn archive_read_support_format_all +enables support for all available formats. +Note that there is no default. +.It Fn archive_read_open +Freeze the settings, open the archive, and prepare for reading entries. +This is the most generic version of this call, which accepts +three callback functions. +Most clients will want to use +.Fn archive_read_open_file +or +.Fn archive_read_open_fd +instead. +The library invokes the client-provided functions to obtain +raw bytes from the archive. +Note: The API permits a decompression method to fork and invoke the +callbacks from another process. +Although none of the current decompression methods use this technique, +future decompression methods may utilize this technique. +If the decompressor forks, it will ensure that the open and close +callbacks are invoked within the same process as the read callback. +In particular, clients should not attempt to use shared variables to +communicate between the open/read/close callbacks and the mainline code. +.It Fn archive_read_open_fd +Like +.Fn archive_read_open , +except that it accepts a file descriptor and block size rather than +a trio of function pointers. +Note that the file descriptor will not be automatically closed at +end-of-archive. +.It Fn archive_read_open_file +Like +.Fn archive_read_open , +except that it accepts a simple filename and a block size. +A NULL filename represents standard input. +.It Fn archive_read_next_header +Read the header for the next entry and return a pointer to +a +.Tn struct archive_entry . +.It Fn archive_read_data +Read data associated with the header just read. +Internally, this is a convenience function that calls +.Fn archive_read_data_block +and fills any gaps with nulls so that callers see a single +continuous stream of data. +.It Fn archive_read_data_block +Return the next available block of data for this entry. +Unlike +.Fn archive_read_data , +the +.Fn archive_read_data_block +function avoids copying data and allows you to correctly handle +sparse files, as supported by some archive formats. +The library guarantees that offsets will increase and that blocks +will not overlap. +Note that the blocks returned from this function can be much larger +than the block size read from disk, due to compression +and internal buffer optimizations. +.It Fn archive_read_data_skip +A convenience function that repeatedly calls +.Fn archive_read_data_block +to skip all of the data for this archive entry. +.It Fn archive_read_data_into_buffer +A convenience function that repeatedly calls +.Fn archive_read_data_block +to copy the entire entry into the client-supplied buffer. +Note that the client is responsible for sizing the buffer appropriately. +.It Fn archive_read_data_into_fd +A convenience function that repeatedly calls +.Fn archive_read_data_block +to copy the entire entry to the provided file descriptor. +.It Fn archive_read_extract +A convenience function that recreates the specified object on +disk and reads the entry data into that object. +The filename, permissions, and other critical information +are taken from the provided +.Va archive_entry +object. +The +.Va flags +argument modifies how the object is recreated. +It consists of a bitwise OR of one or more of the following values: +.Bl -tag -compact -width "indent" +.It Cm ARCHIVE_EXTRACT_OWNER +The user and group IDs should be set on the restored file. +By default, the user and group IDs are not restored. +.It Cm ARCHIVE_EXTRACT_PERM +The permissions (mode bits) should be restored for all objects. +By default, permissions are only restored for regular files. +.It Cm ARCHIVE_EXTRACT_TIME +The timestamps (mtime, ctime, and atime) should be restored. +By default, they are ignored. +Note that restoring of atime is not currently supported. +.It Cm ARCHIVE_EXTRACT_NO_OVERWRITE +Existing files on disk will not be overwritten. +By default, existing regular files are truncated and overwritten; +existing directories will have their permissions updated; +other pre-existing objects are unlinked and recreated from scratch. +.It Cm ARCHIVE_EXTRACT_UNLINK +Existing files on disk will be unlinked and recreated from scratch. +By default, existing files are truncated and rewritten, but +the file is not recreated. +In particular, the default behavior does not break existing hard links. +.It Cm ARCHIVE_EXTRACT_ACL +Attempt to restore ACLs. +By default, extended ACLs are ignored. +.It Cm ARCHIVE_EXTRACT_FFLAGS +Attempt to restore extended file flags. +By default, file flags are ignored. +.El +Note that not all attributes are set immediately; +some attributes are cached in memory and written to disk only +when the archive is closed. +(For example, read-only directories are initially created +writable so that files within those directories can be +restored. +The final permissions are set when the archive is closed.) +.It Fn archive_read_extract_set_progress_callback +Sets a pointer to a user-defined callback that can be used +for updating progress displays during extraction. +The progress function will be invoked during the extraction of large +regular files. +The progress function will be invoked with the pointer provided to this call. +Generally, the data pointed to should include a reference to the archive +object and the archive_entry object so that various statistics +can be retrieved for the progress display. +.It Fn archive_read_close +Complete the archive and invoke the close callback. +.It Fn archive_read_finish +Invokes +.Fn archive_read_close +if it was not invoked manually, then release all resources. +.El +.Pp +Note that the library determines most of the relevant information about +the archive by inspection. +In particular, it automatically detects +.Xr gzip 1 +or +.Xr bzip2 1 +compression and transparently performs the appropriate decompression. +It also automatically detects the archive format. +.Pp +A complete description of the +.Tn struct archive +and +.Tn struct archive_entry +objects can be found in the overview manual page for +.Xr libarchive 3 . +.Sh CLIENT CALLBACKS +The callback functions must match the following prototypes: +.Bl -item -offset indent +.It +.Ft typedef ssize_t +.Fn archive_read_callback "struct archive *" "void *client_data" "const void **buffer" +.It +.Ft typedef int +.Fn archive_open_callback "struct archive *" "void *client_data" +.It +.Ft typedef int +.Fn archive_close_callback "struct archive *" "void *client_data" +.El +.Pp +The open callback is invoked by +.Fn archive_open . +It should return +.Cm ARCHIVE_OK +if the underlying file or data source is successfully +opened. +If the open fails, it should call +.Fn archive_set_error +to register an error code and message and return +.Cm ARCHIVE_FATAL . +.Pp +The read callback is invoked whenever the library +requires raw bytes from the archive. +The read callback should read data into a buffer, +set the +.Li const void **buffer +argument to point to the available data, and +return a count of the number of bytes available. +The library will invoke the read callback again +only after it has consumed this data. +The library imposes no constraints on the size +of the data blocks returned. +On end-of-file, the read callback should +return zero. +On error, the read callback should invoke +.Fn archive_set_error +to register an error code and message and +return -1. +.Pp +The close callback is invoked by archive_close when +the archive processing is complete. +The callback should return +.Cm ARCHIVE_OK +on success. +On failure, the callback should invoke +.Fn archive_set_error +to register an error code and message and +return +.Cm ARCHIVE_FATAL. +.Sh EXAMPLE +The following illustrates basic usage of the library. +In this example, +the callback functions are simply wrappers around the standard +.Xr open 2 , +.Xr read 2 , +and +.Xr close 2 +system calls. +.Bd -literal -offset indent +void +list_archive(const char *name) +{ + struct mydata *mydata; + struct archive *a; + struct archive_entry *entry; + + mydata = malloc(sizeof(struct mydata)); + a = archive_read_new(); + mydata->name = name; + archive_read_support_compression_all(a); + archive_read_support_format_all(a); + archive_read_open(a, mydata, myopen, myread, myclose); + while (archive_read_next_header(a, &entry) == ARCHIVE_OK) { + printf("%s\\n",archive_entry_pathname(entry)); + archive_read_data_skip(a); + } + archive_read_finish(a); + free(mydata); +} + +ssize_t +myread(struct archive *a, void *client_data, const void **buff) +{ + struct mydata *mydata = client_data; + + *buff = mydata->buff; + return (read(mydata->fd, mydata->buff, 10240)); +} + +int +myopen(struct archive *a, void *client_data) +{ + struct mydata *mydata = client_data; + + mydata->fd = open(mydata->name, O_RDONLY); + return (mydata->fd >= 0 ? ARCHIVE_OK : ARCHIVE_FATAL); +} + +int +myclose(struct archive *a, void *client_data) +{ + struct mydata *mydata = client_data; + + if (mydata->fd > 0) + close(mydata->fd); + return (ARCHIVE_OK); +} +.Ed +.Sh RETURN VALUES +Most functions return zero on success, non-zero on error. +The possible return codes include: +.Cm ARCHIVE_OK +(the operation succeeded), +.Cm ARCHIVE_WARN +(the operation succeeded but a non-critical error was encountered), +.Cm ARCHIVE_EOF +(end-of-archive was encountered), +.Cm ARCHIVE_RETRY +(the operation failed but can be retried), +and +.Cm ARCHIVE_FATAL +(there was a fatal error; the archive should be closed immediately). +Detailed error codes and textual descriptions are available from the +.Fn archive_errno +and +.Fn archive_error_string +functions. +.Pp +.Fn archive_read_new +returns a pointer to a freshly allocated +.Tn struct archive +object. +It returns +.Dv NULL +on error. +.Pp +.Fn archive_read_data +returns a count of bytes actually read or zero at the end of the entry. +On error, a value of +.Cm ARCHIVE_FATAL , +.Cm ARCHIVE_WARN , +or +.Cm ARCHIVE_RETRY +is returned and an error code and textual description can be retrieved from the +.Fn archive_errno +and +.Fn archive_error_string +functions. +.Pp +The library expects the client callbacks to behave similarly. +If there is an error, you can use +.Fn archive_set_error +to set an appropriate error code and description, +then return one of the non-zero values above. +(Note that the value eventually returned to the client may +not be the same; many errors that are not critical at the level +of basic I/O can prevent the archive from being properly read, +thus most I/O errors eventually cause +.Cm ARCHIVE_FATAL +to be returned.) +.\" .Sh ERRORS +.Sh SEE ALSO +.Xr tar 1 , +.Xr archive 3 , +.Xr archive_util 3 , +.Xr tar 5 +.Sh HISTORY +The +.Nm libarchive +library first appeared in +.Fx 5.3 . +.Sh AUTHORS +.An -nosplit +The +.Nm libarchive +library was written by +.An Tim Kientzle Aq kientzle@acm.org . +.Sh BUGS +Directories are actually extracted in two distinct phases. +Directories are created during +.Fn archive_read_extract , +but final permissions are not set until +.Fn archive_read_close . +This separation is necessary to correctly handle borderline +cases such as a non-writable directory containing +files, but can cause unexpected results. +In particular, directory permissions are not fully +restored until the archive is closed. +If you use +.Xr chdir 2 +to change the current directory between calls to +.Fn archive_read_extract +or before calling +.Fn archive_read_close , +you may confuse the permission-setting logic with +the result that directory permissions are restored +incorrectly. |
