1 files changed, 250 insertions, 3 deletions

diff --git a/video_player/src/main.cpp b/video_player/src/main.cpp
index 91f2d4b..42a9b4f 100644
--- a/video_player/src/main.cpp
+++ b/video_player/src/main.cpp
@@ -11,8 +11,13 @@
 #include <mutex>
 #include <optional>
 #include <set>
+#include <algorithm>
 
 #include <mpv/client.h>
+#include <mpv/stream_cb.h>
+#include <sys/stat.h>
+#include <signal.h>
+#include <sys/wait.h>
 #include <json/json.h>
 
 #define COMMAND_BUFFER_MAX_SIZE 2048
@@ -313,6 +318,247 @@ static void mpv_set_before_init_options(mpv_handle *mpv_ctx, const Args &args) {
     }
 }
 
+#define READ_END 0
+#define WRITE_END 1
+
+struct ReadProgram {
+    pid_t pid = -1;
+    int read_fd = -1;
+    int64_t offset = 0;
+    int64_t content_length = -1;
+    char *url = nullptr;
+};
+
+static int exec_program_pipe(const char **args, ReadProgram *read_program) {
+    read_program->pid = -1;
+    read_program->read_fd = -1;
+
+    /* 1 arguments */
+    if(args[0] == NULL)
+        return -1;
+    
+    int fd[2];
+    if(pipe(fd) == -1) {
+        perror("Failed to open pipe");
+        return -2;
+    }
+
+    pid_t pid = vfork();
+    if(pid == -1) {
+        perror("Failed to vfork");
+        close(fd[READ_END]);
+        close(fd[WRITE_END]);
+        return -3;
+    } else if(pid == 0) { /* child */
+        dup2(fd[WRITE_END], STDOUT_FILENO);
+        close(fd[READ_END]);
+        close(fd[WRITE_END]);
+
+        execvp(args[0], (char* const*)args);
+        perror("execvp");
+        _exit(127);
+    } else { /* parent */
+        close(fd[WRITE_END]);
+        read_program->pid = pid;
+        read_program->read_fd = fd[READ_END];
+        return 0;
+    }
+}
+
+static char to_upper(char c) {
+    if(c >= 'a' && c <= 'z')
+        return c - 32;
+    else
+        return c;
+}
+
+size_t str_find_case_insensitive(const std::string &str, size_t start_index, const char *substr, size_t substr_len) {
+    if(substr_len == 0)
+        return 0;
+
+    auto it = std::search(str.begin() + start_index, str.end(), substr, substr + substr_len,
+        [](char c1, char c2) {
+            return to_upper(c1) == to_upper(c2);
+        });
+
+    if(it == str.end())
+        return std::string::npos;
+
+    return it - str.begin();
+}
+
+static int64_t size_fn(void *cookie) {
+    ReadProgram *program = (ReadProgram*)cookie;
+    if(program->content_length != -1)
+        return program->content_length;
+
+    const char *args[] = { "curl",
+        "-I",
+        "-H", "Accept-Language: en-US,en;q=0.5", "-H", "Connection: keep-alive",
+        "--no-buffer",
+        "-H", "user-agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.138 Safari/537.36",
+        "-g", "-s", "-L", "-f",
+        "--", program->url, nullptr };
+
+    ReadProgram header_program;
+    int res = exec_program_pipe(args, &header_program);
+    if(res != 0)
+        return MPV_ERROR_UNSUPPORTED;
+
+    std::string buffer;
+    buffer.resize(8192);
+    size_t read_offset = 0;
+    for(;;) {
+        ssize_t bytes_read = read(header_program.read_fd, &buffer[read_offset], buffer.size() - read_offset);
+        if(bytes_read == 0) {
+            buffer.resize(read_offset);
+            break;
+        } else if(bytes_read == -1) {
+            res = MPV_ERROR_UNSUPPORTED;
+            break;
+        }
+
+        read_offset += bytes_read;
+        if(read_offset >= buffer.size()) {
+            fprintf(stderr, "Error: youtube header too large\n");
+            res = MPV_ERROR_UNSUPPORTED;
+            break;
+        }
+    }
+
+    if(res != 0)
+        kill(header_program.pid, SIGTERM);
+
+    int status = 0;
+    if(waitpid(header_program.pid, &status, 0) == -1) {
+        perror("waitpid failed");
+        res = MPV_ERROR_UNSUPPORTED;
+        goto cleanup;
+    }
+
+    if(!WIFEXITED(status)) {
+        res = MPV_ERROR_UNSUPPORTED;
+        goto cleanup;
+    }
+
+    if(WEXITSTATUS(status) != 0)
+        res = MPV_ERROR_UNSUPPORTED;
+
+    cleanup:
+    close(header_program.read_fd);
+
+    if(res == 0) {
+        size_t content_length_index = str_find_case_insensitive(buffer, 0, "content-length:", 15);
+        if(content_length_index == std::string::npos)
+            return res;
+
+        content_length_index += 15;
+        size_t content_length_end = buffer.find('\r', content_length_index);
+        if(content_length_end == std::string::npos)
+            return res;
+
+        buffer[content_length_end] = '\0';
+        errno = 0;
+        char *endptr;
+        int64_t content_length = strtoll(&buffer[content_length_index], &endptr, 10);
+        if(endptr == &buffer[content_length_index] || errno != 0)
+            return res;
+
+        res = content_length;
+    }
+
+    program->content_length = res;
+    return res;
+}
+
+static int64_t seek_fn(void *cookie, int64_t offset) {
+    ReadProgram *program = (ReadProgram*)cookie;
+
+    if(program->pid != -1) {
+        kill(program->pid, SIGTERM);
+        int status;
+        waitpid(program->pid, &status, 0);
+        program->pid = -1;
+    }
+
+    if(program->read_fd != -1) {
+        close(program->read_fd);
+        program->read_fd = -1;
+    }
+
+    program->offset = offset;
+
+    char range[64];
+    snprintf(range, sizeof(range), "%lld-%lld", (long long)program->offset, (long long)program->offset + 5242870LL);
+    const char *args[] = { "curl",
+        "-H", "Accept-Language: en-US,en;q=0.5", "-H", "Connection: keep-alive",
+        "--no-buffer",
+        "-H", "user-agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.138 Safari/537.36",
+        "-g", "-s", "-L", "-f",
+        "-r", range, "--", program->url, nullptr };
+    int res = exec_program_pipe(args, program);
+    if(res != 0)
+        return MPV_ERROR_GENERIC;
+
+    return offset;
+}
+
+static int64_t read_fn(void *cookie, char *buf, uint64_t nbytes) {
+    ReadProgram *program = (ReadProgram*)cookie;
+    ssize_t bytes_read = read(program->read_fd, buf, nbytes);
+    if(bytes_read > 0) {
+        program->offset += bytes_read;
+    } else if(bytes_read == 0) {
+        // End of current range, progress to next range
+        bytes_read = seek_fn(program, program->offset);
+        if(bytes_read >= 0) {
+            bytes_read = read(program->read_fd, buf, nbytes);
+            if(bytes_read > 0)
+                program->offset += bytes_read;
+        }
+    }
+    return bytes_read;
+}
+
+static void close_fn(void *cookie) {
+    ReadProgram *program = (ReadProgram*)cookie;
+
+    if(program->pid != -1) {
+        kill(program->pid, SIGTERM);
+        int status;
+        waitpid(program->pid, &status, 0);
+        program->pid = -1;
+    }
+
+    if(program->read_fd != -1) {
+        close(program->read_fd);
+        program->read_fd = -1;
+    }
+
+    if(program->url) {
+        free(program->url);
+        program->url = nullptr;
+    }
+
+    delete program;
+}
+
+static int open_fn(void*, char *uri, mpv_stream_cb_info *info) {
+    ReadProgram *read_program = new ReadProgram();
+    read_program->read_fd = -1;
+    read_program->pid = -1;
+    read_program->url = strdup((const char*)uri + 8);
+    read_program->offset = 0;
+    int64_t res = seek_fn(read_program, read_program->offset);
+
+    info->cookie = read_program;
+    info->size_fn = size_fn;
+    info->read_fn = read_fn;
+    info->seek_fn = seek_fn;
+    info->close_fn = close_fn;
+    return res >= 0 ? 0 : MPV_ERROR_LOADING_FAILED;
+}
+
 int main(int argc, char **argv) {
     // This is needed for mpv_create or it will fail
     setlocale(LC_ALL, "C");
@@ -328,12 +574,13 @@ int main(int argc, char **argv) {
     mpv_set_before_init_options(mpv_ctx, args);
     check_error(mpv_initialize(mpv_ctx), "mpv_initialize");
 
-    const char *cmd[] = { "loadfile", args.file_to_play, NULL };
-    check_error(mpv_command(mpv_ctx, cmd), "loadfile");
-
+    check_error(mpv_stream_cb_add_ro(mpv_ctx, "qm-yt", nullptr, open_fn), "mpv_stream_cb_add_ro");
     check_error(mpv_observe_property(mpv_ctx, 0, "idle-active", MPV_FORMAT_FLAG), "observe idle-active");
     check_error(mpv_observe_property(mpv_ctx, 0, "fullscreen", MPV_FORMAT_FLAG), "observe fullscreen");
 
+    const char *cmd[] = { "loadfile", args.file_to_play, NULL };
+    check_error(mpv_command(mpv_ctx, cmd), "loadfile");
+
     char command_buffer[COMMAND_BUFFER_MAX_SIZE];
     size_t command_buffer_size = 0;
     std::mutex command_mutex;