diff options
| -rw-r--r-- | docs/examples/Makefile.am | 11 | ||||
| -rw-r--r-- | docs/examples/fopen.c | 222 |
2 files changed, 228 insertions, 5 deletions
diff --git a/docs/examples/Makefile.am b/docs/examples/Makefile.am index 13634302e..c0c82f3b5 100644 --- a/docs/examples/Makefile.am +++ b/docs/examples/Makefile.am @@ -4,11 +4,12 @@ AUTOMAKE_OPTIONS = foreign no-dependencies -EXTRA_DIST = README curlgtk.c sepheaders.c simple.c postit2.c \ - win32sockets.c persistant.c ftpget.c Makefile.example \ - multithread.c getinmemory.c ftpupload.c httpput.c \ - simplessl.c ftpgetresp.c http-post.c post-callback.c \ - multi-app.c multi-double.c multi-single.c multi-post.c +EXTRA_DIST = README curlgtk.c sepheaders.c simple.c postit2.c \ + win32sockets.c persistant.c ftpget.c Makefile.example \ + multithread.c getinmemory.c ftpupload.c httpput.c \ + simplessl.c ftpgetresp.c http-post.c post-callback.c \ + multi-app.c multi-double.c multi-single.c multi-post.c \ + fopen.c all: @echo "done" diff --git a/docs/examples/fopen.c b/docs/examples/fopen.c new file mode 100644 index 000000000..a60d10334 --- /dev/null +++ b/docs/examples/fopen.c @@ -0,0 +1,222 @@ +/***************************************************************************** + * _ _ ____ _ + * Project ___| | | | _ \| | + * / __| | | | |_) | | + * | (__| |_| | _ <| |___ + * \___|\___/|_| \_\_____| + * + * $Id$ + * + * This example source code introduces an fopen()/fread()/fclose() emulation + * for URL reads. Using an approach similar to this, you could replace your + * program's fopen() with this url_fopen() and fread() with url_fread() and + * it should be possible to read remote streams instead of (only) local files. + * + * See the main() function at the bottom that shows a tiny app in action. + * + * This source code is a proof of concept. It will need further attention to + * become production-use useful and solid. + * + * This example requires libcurl 7.9.7 or later. + */ +#include <stdio.h> +#include <string.h> +#include <sys/time.h> + +#include <curl/curl.h> +#include <curl/types.h> +#include <curl/easy.h> + +struct data { + int type; + union { + CURL *curl; + FILE *file; + } handle; + + /* TODO: We should perhaps document the biggest possible buffer chunk we can + get from libcurl in one single callback... */ + char buffer[CURL_MAX_WRITE_SIZE]; + + char *readptr; /* read from here */ + int bytes; /* bytes available from read pointer */ + + CURLMcode m; /* stored from a previous url_fread() */ +}; + +typedef struct data URL_FILE; + +/* we use a global one for convenience */ +CURLM *multi_handle; + +static +size_t write_callback(char *buffer, + size_t size, + size_t nitems, + void *userp) +{ + URL_FILE *url = (URL_FILE *)userp; + size *= nitems; + + memcpy(url->readptr, buffer, size); + url->readptr += size; + url->bytes += size; + + return size; +} + +URL_FILE *url_fopen(char *url, char *operation) +{ + /* this code could check for URLs or types in the 'url' and + basicly use the real fopen() for standard files */ + + URL_FILE *file; + int still_running; + + file = (URL_FILE *)malloc(sizeof(URL_FILE)); + if(!file) + return NULL; + + memset(file, 0, sizeof(URL_FILE)); + + file->type = 1; /* marked as URL, use 0 for plain file */ + file->handle.curl = curl_easy_init(); + + curl_easy_setopt(file->handle.curl, CURLOPT_URL, url); + curl_easy_setopt(file->handle.curl, CURLOPT_FILE, file); + curl_easy_setopt(file->handle.curl, CURLOPT_VERBOSE, FALSE); + curl_easy_setopt(file->handle.curl, CURLOPT_WRITEFUNCTION, write_callback); + + if(!multi_handle) + multi_handle = curl_multi_init(); + + curl_multi_add_handle(multi_handle, file->handle.curl); + + while(CURLM_CALL_MULTI_PERFORM == + curl_multi_perform(multi_handle, &still_running)); + + /* if still_running would be 0 now, we should return NULL */ + + return file; +} + +void url_fclose(URL_FILE *file) +{ + /* make sure the easy handle is not in the multi handle anymore */ + curl_multi_remove_handle(multi_handle, file->handle.curl); + + /* cleanup */ + curl_easy_cleanup(file->handle.curl); +} + + + +size_t url_fread(void *ptr, size_t size, size_t nmemb, URL_FILE *file) +{ + fd_set fdread; + fd_set fdwrite; + fd_set fdexcep; + int maxfd; + struct timeval timeout; + int rc; + int still_running = 0; + + if(!file->bytes) { /* no data available at this point */ + + file->readptr = file->buffer; /* reset read pointer */ + + if(CURLM_CALL_MULTI_PERFORM == file->m) { + while(CURLM_CALL_MULTI_PERFORM == + curl_multi_perform(multi_handle, &still_running)) { + if(file->bytes) { + printf("(fread) WOAH! THis happened!\n"); + break; + } + } + if(!still_running) { + printf("NO MORE RUNNING AROUND!\n"); + return 0; + } + } + + FD_ZERO(&fdread); + FD_ZERO(&fdwrite); + FD_ZERO(&fdexcep); + + /* set a suitable timeout to fail on */ + timeout.tv_sec = 500; /* 5 minutes */ + timeout.tv_usec = 0; + + /* get file descriptors from the transfers */ + curl_multi_fdset(multi_handle, &fdread, &fdwrite, &fdexcep, &maxfd); + + rc = select(maxfd+1, &fdread, &fdwrite, &fdexcep, &timeout); + + switch(rc) { + case -1: + /* select error */ + break; + case 0: + break; + default: + /* timeout or readable/writable sockets */ + do { + file->m = curl_multi_perform(multi_handle, &still_running); + + if(file->bytes) + /* we have received data, return that now */ + break; + + } while(CURLM_CALL_MULTI_PERFORM == file->m); + + + if(!still_running) + printf("NO MORE RUNNING AROUND!\n"); + + break; + } + } + else + printf("(fread) Skip network read\n"); + + if(file->bytes) { + /* data already available, return that */ + int want = size * nmemb; + + if(file->bytes < want) + want = file->bytes; + + memcpy(ptr, file->readptr, want); + file->readptr += want; + file->bytes -= want; + + printf("(fread) return %d bytes\n", want); + + return want; + } + return 0; /* no data available to return */ +} + + +int main(int argc, char *argv[]) +{ + URL_FILE *handle; + int nread; + char buffer[256]; + + handle = url_fopen("http://www.haxx.se", "r"); + + if(!handle) { + printf("couldn't url_fopen()\n"); + } + + do { + nread = url_fread(buffer, sizeof(buffer), 1, handle); + + printf("We got: %d bytes\n", nread); + } while(nread); + + url_fclose(handle); + + return 0; +} |