2024年C C++最全C语言curl实现FTP上传、下载、获取文件信息(2)，2024年最新手慢无

于 2024-05-12 22:49:32 发布
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}


## Get a single file from an FTPS server.2

/***************************************************************************

  •                              _   _ ____  _
  • Project ___| | | | _ | |
  •                         / __| | | | |_) | |

  •                        | (__| |_| |  _ <| |___

  •                         \___|\___/|_| \_\_____|
  • Copyright © 1998 - 2019, Daniel Stenberg, daniel@haxx.se, et al.
  • This software is licensed as described in the file COPYING, which
  • you should have received as part of this distribution. The terms
  • are also available at https://curl.haxx.se/docs/copyright.html.
  • You may opt to use, copy, modify, merge, publish, distribute and/or sell
  • copies of the Software, and permit persons to whom the Software is
  • furnished to do so, under the terms of the COPYING file.
  • This software is distributed on an “AS IS” basis, WITHOUT WARRANTY OF ANY
  • KIND, either express or implied.

***************************************************************************/

#include <stdio.h>

#include <curl/curl.h>

/*

  • Get a single file from an FTPS server.

*/

struct FtpFile {
const char *filename;
FILE *stream;
};

static size_t my_fwrite(void *buffer, size_t size, size_t nmemb,
void *stream)
{
struct FtpFile *out = (struct FtpFile )stream;
if(!out->stream) {
/ open file for writing /
out->stream = fopen(out->filename, “wb”);
if(!out->stream)
return -1; / failure, can’t open file to write */
}
return fwrite(buffer, size, nmemb, out->stream);
}

int main(void)
{
CURL curl;
CURLcode res;
struct FtpFile ftpfile = {
“yourfile.txt”, / name to store the file as if successful */
NULL
};

curl_global_init(CURL_GLOBAL_DEFAULT);

curl = curl_easy_init();
if(curl) {
/*
* You better replace the URL with one that works! Note that we use an
* FTP:// URL with standard explicit FTPS. You can also do FTPS:// URLs if
* you want to do the rarer kind of transfers: implicit.
/
curl_easy_setopt(curl, CURLOPT_URL,
“http://10.170.6.66/testfile”);
/ Define our callback to get called when there’s data to be written /
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, my_fwrite);
/ Set a pointer to our struct to pass to the callback */
curl_easy_setopt(curl, CURLOPT_WRITEDATA, &ftpfile);

/* We activate SSL and we require it for both control and data */
curl_easy_setopt(curl, CURLOPT_USE_SSL, CURLUSESSL_ALL);

/* Switch on full protocol/debug output */
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);

res = curl_easy_perform(curl);

/* always cleanup */
curl_easy_cleanup(curl);

if(CURLE_OK != res) {
  /* we failed */
  fprintf(stderr, "curl told us %d\n", res);
}

}

if(ftpfile.stream)
fclose(ftpfile.stream); /* close the local file */

curl_global_cleanup();

return 0;
}


## Performs an FTP upload and renames the file just after a successful transfer.

/***************************************************************************

  •                              _   _ ____  _
  • Project ___| | | | _ | |
  •                         / __| | | | |_) | |

  •                        | (__| |_| |  _ <| |___

  •                         \___|\___/|_| \_\_____|
  • Copyright © 1998 - 2019, Daniel Stenberg, daniel@haxx.se, et al.
  • This software is licensed as described in the file COPYING, which
  • you should have received as part of this distribution. The terms
  • are also available at https://curl.haxx.se/docs/copyright.html.
  • You may opt to use, copy, modify, merge, publish, distribute and/or sell
  • copies of the Software, and permit persons to whom the Software is
  • furnished to do so, under the terms of the COPYING file.
  • This software is distributed on an “AS IS” basis, WITHOUT WARRANTY OF ANY
  • KIND, either express or implied.

***************************************************************************/
#include <stdio.h>
#include <string.h>

#include <curl/curl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#ifdef WIN32
#include <io.h>
#else
#include <unistd.h>
#endif

/*

  • Performs an FTP upload and renames the file just after a successful
  • transfer.

*/

//#define LOCAL_FILE “/tmp/uploadthis.txt”
//#define UPLOAD_FILE_AS “while-uploading.txt”
//#define REMOTE_URL “ftp://example.com/” UPLOAD_FILE_AS
//#define RENAME_FILE_TO “renamed-and-fine.txt”

#define LOCAL_FILE “uploadthis.txt”
#define UPLOAD_FILE_AS “while-uploading.txt”
#define REMOTE_URL “http://10.170.6.66/”
#define RENAME_FILE_TO “renamed-and-fine.txt”

/* NOTE: if you want this example to work on Windows with libcurl as a
DLL, you MUST also provide a read callback with CURLOPT_READFUNCTION.
Failing to do so will give you a crash since a DLL may not use the
variable’s memory when passed in to it from an app like this. */
static size_t read_callback(void *ptr, size_t size, size_t nmemb, void stream)
{
curl_off_t nread;
/ in real-world cases, this would probably get this data differently
as this fread() stuff is exactly what the library already would do
by default internally */
size_t retcode = fread(ptr, size, nmemb, stream);

nread = (curl_off_t)retcode;

fprintf(stderr, “*** We read %” CURL_FORMAT_CURL_OFF_T
" bytes from file\n", nread);
return retcode;
}

int main(void)
{
CURL *curl;
CURLcode res;
FILE *hd_src;
struct stat file_info;
curl_off_t fsize;

struct curl_slist *headerlist = NULL;
static const char buf_1 [] = "RNFR " UPLOAD_FILE_AS;
static const char buf_2 [] = "RNTO " RENAME_FILE_TO;

/* get the file size of the local file */
if(stat(LOCAL_FILE, &file_info)) {
printf(“Couldn’t open ‘%s’: %s\n”, LOCAL_FILE, strerror(errno));
return 1;
}
fsize = (curl_off_t)file_info.st_size;

printf(“Local file size: %” CURL_FORMAT_CURL_OFF_T " bytes.\n", fsize);

/* get a FILE * of the same file */
hd_src = fopen(LOCAL_FILE, “rb”);

/* In windows, this will init the winsock stuff */
curl_global_init(CURL_GLOBAL_ALL);

/* get a curl handle /
curl = curl_easy_init();
if(curl) {
/ build a list of commands to pass to libcurl */
headerlist = curl_slist_append(headerlist, buf_1);
headerlist = curl_slist_append(headerlist, buf_2);

/* we want to use our own read function */
curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_callback);

/* enable uploading */
curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);

/* specify target */
curl_easy_setopt(curl, CURLOPT_URL, REMOTE_URL);

/* pass in that last of FTP commands to run after the transfer */
curl_easy_setopt(curl, CURLOPT_POSTQUOTE, headerlist);

/* now specify which file to upload */
curl_easy_setopt(curl, CURLOPT_READDATA, hd_src);

/* Set the size of the file to upload (optional).  If you give a *_LARGE
   option you MUST make sure that the type of the passed-in argument is a
   curl_off_t. If you use CURLOPT_INFILESIZE (without _LARGE) you must
   make sure that to pass in a type 'long' argument. */
curl_easy_setopt(curl, CURLOPT_INFILESIZE_LARGE,
                 (curl_off_t)fsize);

/* Now run off and do what you've been told! */
res = curl_easy_perform(curl);
/* Check for errors */
if(res != CURLE_OK)
  fprintf(stderr, "curl_easy_perform() failed: %s\n",
          curl_easy_strerror(res));

/* clean up the FTP commands list */
curl_slist_free_all(headerlist);

/* always cleanup */
curl_easy_cleanup(curl);

}
fclose(hd_src); /* close the local file */

curl_global_cleanup();
return 0;
}


## FTP upload a file from memory

/***************************************************************************

  •                              _   _ ____  _
  • Project ___| | | | _ | |
  •                         / __| | | | |_) | |

  •                        | (__| |_| |  _ <| |___

  •                         \___|\___/|_| \_\_____|
  • Copyright © 1998 - 2017, Daniel Stenberg, daniel@haxx.se, et al.
  • This software is licensed as described in the file COPYING, which
  • you should have received as part of this distribution. The terms
  • are also available at https://curl.haxx.se/docs/copyright.html.
  • You may opt to use, copy, modify, merge, publish, distribute and/or sell
  • copies of the Software, and permit persons to whom the Software is
  • furnished to do so, under the terms of the COPYING file.
  • This software is distributed on an “AS IS” basis, WITHOUT WARRANTY OF ANY
  • KIND, either express or implied.

**************************************************************************/
/

  • FTP upload a file from memory

*/
#include <stdio.h>
#include <string.h>
#include <curl/curl.h>

static const char data[]=
"Lorem ipsum dolor sit amet, consectetur adipiscing elit. "
"Nam rhoncus odio id venenatis volutpat. Vestibulum dapibus "
"bibendum ullamcorper. Maecenas finibus elit augue, vel "
"condimentum odio maximus nec. In hac habitasse platea dictumst. "
"Vestibulum vel dolor et turpis rutrum finibus ac at nulla. "
"Vivamus nec neque ac elit blandit pretium vitae maximus ipsum. "
"Quisque sodales magna vel erat auctor, sed pellentesque nisi "
"rhoncus. Donec vehicula maximus pretium. Aliquam eu tincidunt "
“lorem.”;

struct WriteThis {
const char *readptr;
size_t sizeleft;
};

static size_t read_callback(void *ptr, size_t size, size_t nmemb, void *userp)
{
struct WriteThis *upload = (struct WriteThis )userp;
size_t max = sizenmemb;

if(max < 1)
return 0;

if(upload->sizeleft) {
size_t copylen = max;
if(copylen > upload->sizeleft)
copylen = upload->sizeleft;
memcpy(ptr, upload->readptr, copylen);
upload->readptr += copylen;
upload->sizeleft -= copylen;
return copylen;
}

return 0; /* no more data left to deliver */
}

int main(void)
{
CURL *curl;
CURLcode res;

struct WriteThis upload;

upload.readptr = data;
upload.sizeleft = strlen(data);

/* In windows, this will init the winsock stuff /
res = curl_global_init(CURL_GLOBAL_DEFAULT);
/ Check for errors */
if(res != CURLE_OK) {
fprintf(stderr, “curl_global_init() failed: %s\n”,
curl_easy_strerror(res));
return 1;
}

/* get a curl handle /
curl = curl_easy_init();
if(curl) {
/ First set the URL, the target file */
curl_easy_setopt(curl, CURLOPT_URL,
“ftp://example.com/path/to/upload/file”);

/* User and password for the FTP login */
curl_easy_setopt(curl, CURLOPT_USERPWD, "login:secret");

/* Now specify we want to UPLOAD data */
curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);

/* we want to use our own read function */
curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_callback);

/* pointer to pass to our read function */
curl_easy_setopt(curl, CURLOPT_READDATA, &upload);

/* get verbose debug output please */
curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);

/* Set the expected upload size. */
curl_easy_setopt(curl, CURLOPT_INFILESIZE_LARGE,
                 (curl_off_t)upload.sizeleft);

/* Perform the request, res will get the return code */
res = curl_easy_perform(curl);
/* Check for errors */
if(res != CURLE_OK)
  fprintf(stderr, "curl_easy_perform() failed: %s\n",
          curl_easy_strerror(res));

/* always cleanup */
curl_easy_cleanup(curl);

}
curl_global_cleanup();
return 0;
}


## Upload to FTP, resuming failed transfers.

/***************************************************************************

  •                              _   _ ____  _
  • Project ___| | | | _ | |
  •                         / __| | | | |_) | |

  •                        | (__| |_| |  _ <| |___

  •                         \___|\___/|_| \_\_____|
  • Copyright © 1998 - 2017, Daniel Stenberg, daniel@haxx.se, et al.
  • This software is licensed as described in the file COPYING, which
  • you should have received as part of this distribution. The terms
  • are also available at https://curl.haxx.se/docs/copyright.html.
  • You may opt to use, copy, modify, merge, publish, distribute and/or sell
  • copies of the Software, and permit persons to whom the Software is
  • furnished to do so, under the terms of the COPYING file.
  • This software is distributed on an “AS IS” basis, WITHOUT WARRANTY OF ANY
  • KIND, either express or implied.

**************************************************************************/
/

  • Upload to FTP, resuming failed transfers.

*/

#include <stdlib.h>
#include <stdio.h>
#include <curl/curl.h>

/* parse headers for Content-Length */
static size_t getcontentlengthfunc(void *ptr, size_t size, size_t nmemb,
void *stream)
{
int r;
long len = 0;

r = sscanf(ptr, “Content-Length: %ld\n”, &len);
if®
*((long *) stream) = len;

return size * nmemb;
}

/* discard downloaded data */
static size_t discardfunc(void *ptr, size_t size, size_t nmemb, void *stream)
{
(void)ptr;
(void)stream;
return size * nmemb;
}

/* read data to upload */
static size_t readfunc(void *ptr, size_t size, size_t nmemb, void *stream)
{
FILE *f = stream;
size_t n;

if(ferror(f))
return CURL_READFUNC_ABORT;

n = fread(ptr, size, nmemb, f) * size;

return n;
}

static int upload(CURL *curlhandle, const char *remotepath,
const char *localpath, long timeout, long tries)
{
FILE *f;
long uploaded_len = 0;
CURLcode r = CURLE_GOT_NOTHING;
int c;

f = fopen(localpath, “rb”);
if(!f) {
perror(NULL);
return 0;
}

curl_easy_setopt(curlhandle, CURLOPT_UPLOAD, 1L);

curl_easy_setopt(curlhandle, CURLOPT_URL, remotepath);

if(timeout)
curl_easy_setopt(curlhandle, CURLOPT_FTP_RESPONSE_TIMEOUT, timeout);

curl_easy_setopt(curlhandle, CURLOPT_HEADERFUNCTION, getcontentlengthfunc);
curl_easy_setopt(curlhandle, CURLOPT_HEADERDATA, &uploaded_len);

curl_easy_setopt(curlhandle, CURLOPT_WRITEFUNCTION, discardfunc);

curl_easy_setopt(curlhandle, CURLOPT_READFUNCTION, readfunc);
curl_easy_setopt(curlhandle, CURLOPT_READDATA, f);

/* disable passive mode */
curl_easy_setopt(curlhandle, CURLOPT_FTPPORT, “-”);
curl_easy_setopt(curlhandle, CURLOPT_FTP_CREATE_MISSING_DIRS, 1L);

curl_easy_setopt(curlhandle, CURLOPT_VERBOSE, 1L);

for(c = 0; (r != CURLE_OK) && (c < tries); c++) {
/* are we resuming? /
if© { / yes /
/ determine the length of the file already written */

  /*
   * With NOBODY and NOHEADER, libcurl will issue a SIZE
   * command, but the only way to retrieve the result is
   * to parse the returned Content-Length header. Thus,
   * getcontentlengthfunc(). We need discardfunc() above
   * because HEADER will dump the headers to stdout
   * without it.
   */
  curl_easy_setopt(curlhandle, CURLOPT_NOBODY, 1L);
  curl_easy_setopt(curlhandle, CURLOPT_HEADER, 1L);

  r = curl_easy_perform(curlhandle);
  if(r != CURLE_OK)
    continue;

  curl_easy_setopt(curlhandle, CURLOPT_NOBODY, 0L);
  curl_easy_setopt(curlhandle, CURLOPT_HEADER, 0L);

  fseek(f, uploaded_len, SEEK_SET);

  curl_easy_setopt(curlhandle, CURLOPT_APPEND, 1L);

img
img

网上学习资料一大堆，但如果学到的知识不成体系，遇到问题时只是浅尝辄止，不再深入研究，那么很难做到真正的技术提升。

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一个人可以走的很快，但一群人才能走的更远！不论你是正从事IT行业的老鸟或是对IT行业感兴趣的新人，都欢迎加入我们的的圈子（技术交流、学习资源、职场吐槽、大厂内推、面试辅导），让我们一起学习成长！

  curl_easy_setopt(curlhandle, CURLOPT_NOBODY, 0L);
  curl_easy_setopt(curlhandle, CURLOPT_HEADER, 0L);

  fseek(f, uploaded_len, SEEK_SET);

  curl_easy_setopt(curlhandle, CURLOPT_APPEND, 1L);

[外链图片转存中…(img-7eijAegl-1715525349220)]
[外链图片转存中…(img-VnbGLBpu-1715525349220)]

网上学习资料一大堆，但如果学到的知识不成体系，遇到问题时只是浅尝辄止，不再深入研究，那么很难做到真正的技术提升。

需要这份系统化的资料的朋友，可以添加戳这里获取

一个人可以走的很快，但一群人才能走的更远！不论你是正从事IT行业的老鸟或是对IT行业感兴趣的新人，都欢迎加入我们的的圈子（技术交流、学习资源、职场吐槽、大厂内推、面试辅导），让我们一起学习成长！

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