diff options
Diffstat (limited to 'v4l2-apps/libv4l/libv4lconvert/helper.c')
| -rw-r--r-- | v4l2-apps/libv4l/libv4lconvert/helper.c | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/v4l2-apps/libv4l/libv4lconvert/helper.c b/v4l2-apps/libv4l/libv4lconvert/helper.c new file mode 100644 index 000000000..c1d55c2e5 --- /dev/null +++ b/v4l2-apps/libv4l/libv4lconvert/helper.c @@ -0,0 +1,224 @@ +/* +# (C) 2009 Hans de Goede <hdegoede@redhat.com> + +# This program 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. +# +# This program 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 this program; if not, write to the Free Software +# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA +*/ + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <errno.h> +#include <string.h> +#include <signal.h> +#include <sys/wait.h> +#include "libv4lconvert-priv.h" + +#define READ_END 0 +#define WRITE_END 1 + +/* <sigh> Unfortunately I've failed in contact some Authors of decompression + code of out of tree drivers. So I've no permission to relicense their code + their code from GPL to LGPL. To work around this, these decompression + algorithms are put in separate executables and we pipe data through these + to decompress. + + The "protocol" is very simple: + + From libv4l to the helper the following is send: + int width + int height + int flags + int data length + unsigned char[] data (data length long) + + From the helper to libv4l the following is send: + int data length (-1 in case of a decompression error) + unsigned char[] data (not present when a decompression error happened) +*/ + +static int v4lconvert_helper_start(struct v4lconvert_data *data, + const char *helper) +{ + if (pipe(data->decompress_in_pipe)) { + V4LCONVERT_ERR("with helper pipe: %s\n", strerror(errno)); + goto error; + } + + if (pipe(data->decompress_out_pipe)) { + V4LCONVERT_ERR("with helper pipe: %s\n", strerror(errno)); + goto error_close_in_pipe; + } + + data->decompress_pid = fork(); + if (data->decompress_pid == -1) { + V4LCONVERT_ERR("with helper fork: %s\n", strerror(errno)); + goto error_close_out_pipe; + } + + if (data->decompress_pid == 0) { + /* We are the child */ + + /* Closed unused read / write end of the pipes */ + close(data->decompress_out_pipe[WRITE_END]); + close(data->decompress_in_pipe[READ_END]); + + /* Connect stdin / out to the pipes */ + if (dup2(data->decompress_out_pipe[READ_END], STDIN_FILENO) == -1) { + perror("libv4lconvert: error with helper dup2"); + exit(1); + } + if (dup2(data->decompress_in_pipe[WRITE_END], STDOUT_FILENO) == -1) { + perror("libv4lconvert: error with helper dup2"); + exit(1); + } + + /* And execute the helper */ + execl(helper, helper, NULL); + + /* We should never get here */ + perror("libv4lconvert: error starting helper"); + exit(1); + } else { + /* Closed unused read / write end of the pipes */ + close(data->decompress_out_pipe[READ_END]); + close(data->decompress_in_pipe[WRITE_END]); + } + + return 0; + +error_close_out_pipe: + close(data->decompress_out_pipe[READ_END]); + close(data->decompress_out_pipe[WRITE_END]); +error_close_in_pipe: + close(data->decompress_in_pipe[READ_END]); + close(data->decompress_in_pipe[WRITE_END]); +error: + return -1; +} + +/* IMPROVE ME: we could block SIGPIPE here using pthread_sigmask() + and then in case of EPIPE consume the signal using + sigtimedwait (we need to check if a blocked signal wasn't present + before the write, otherwise we will consume that) and + after consuming the signal try to restart the helper. + + Note we currently do not do this, as SIGPIPE only happens if the + decompressor crashes, which in case of an embedded decompressor + would mean end of program, so by not handling SIGPIPE we treat + external decompressors identical. */ +static int v4lconvert_helper_write(struct v4lconvert_data *data, + const void *b, size_t count) +{ + const unsigned char *buf = b; + const int *i = b; + size_t ret, written = 0; + + while (written < count) { + ret = write(data->decompress_out_pipe[WRITE_END], buf + written, + count - written); + if (ret == -1) { + if (errno == EINTR) + continue; + + V4LCONVERT_ERR("writing to helper: %s\n", strerror(errno)); + return -1; + } + written += ret; + } + + return 0; +} + +static int v4lconvert_helper_read(struct v4lconvert_data *data, void *b, + size_t count) +{ + unsigned char *buf = b; + size_t ret, r = 0; + + while (r < count) { + ret = read(data->decompress_in_pipe[READ_END], buf + r, count - r); + if (ret == -1) { + if (errno == EINTR) + continue; + + V4LCONVERT_ERR("reading from helper: %s\n", strerror(errno)); + return -1; + } + if (ret == 0) { + V4LCONVERT_ERR("reading from helper: unexpected EOF\n"); + return -1; + } + r += ret; + } + + return 0; +} + +int v4lconvert_helper_decompress(struct v4lconvert_data *data, + const char *helper, const unsigned char *src, int src_size, + unsigned char *dest, int dest_size, int width, int height, int flags) +{ + int r; + + if (data->decompress_pid == -1) { + if (v4lconvert_helper_start(data, helper)) + return -1; + } + + if (v4lconvert_helper_write(data, &width, sizeof(int))) + return -1; + + if (v4lconvert_helper_write(data, &height, sizeof(int))) + return -1; + + if (v4lconvert_helper_write(data, &flags, sizeof(int))) + return -1; + + if (v4lconvert_helper_write(data, &src_size, sizeof(int))) + return -1; + + if (v4lconvert_helper_write(data, src, src_size)) + return -1; + + if (v4lconvert_helper_read(data, &r, sizeof(int))) + return -1; + + if (r < 0) { + V4LCONVERT_ERR("decompressing frame data\n"); + return -1; + } + + if (dest_size < r) { + V4LCONVERT_ERR("destination buffer to small\n"); + return -1; + } + + return v4lconvert_helper_read(data, dest, r); +} + +void v4lconvert_helper_cleanup(struct v4lconvert_data *data) +{ + int status; + + if (data->decompress_pid != -1) { + kill(data->decompress_pid, SIGTERM); + waitpid(data->decompress_pid, &status, 0); + + close(data->decompress_out_pipe[WRITE_END]); + close(data->decompress_in_pipe[READ_END]); + + data->decompress_pid = -1; + } +} |