build: avoid overriding system open and stat symbols

Replace them by `curlx_open()` and `curlx_stat()`.

To make it obvious in the source code what is being executed.

Also:
- tests/server: stop overriding `open()` for test servers.
  This is critical for the call made from the signal handler.
  For other calls, it's an option to use `curlx_open()`, but
  doesn't look important enough to do it, following the path
  taken with `fopen()`.

Follow-up to 10bac43b87 #18774
Follow-up to 20142f5d06 #18634
Follow-up to bf7375ecc5 #18503

Closes #18776

src/tool_cb_wrt.c

@@ -23,11 +23,6 @@
  ***************************************************************************/
 #include "tool_setup.h"
 
-#ifdef HAVE_FCNTL_H
-/* for open() */
-#include <fcntl.h>
-#endif
-
 #include "tool_cfgable.h"
 #include "tool_msgs.h"
 #include "tool_cb_wrt.h"
@@ -60,7 +55,8 @@ bool tool_create_output_file(struct OutStruct *outs,
   else {
     int fd;
     do {
-      fd = open(fname, O_CREAT | O_WRONLY | O_EXCL | CURL_O_BINARY, OPENMODE);
+      fd = curlx_open(fname, O_CREAT | O_WRONLY | O_EXCL | CURL_O_BINARY,
+                      OPENMODE);
       /* Keep retrying in the hope that it is not interrupted sometime */
       /* !checksrc! disable ERRNOVAR 1 */
     } while(fd == -1 && errno == EINTR);
@@ -78,8 +74,9 @@ bool tool_create_output_file(struct OutStruct *outs,
           return FALSE;
         next_num++;
         do {
-          fd = open(curlx_dyn_ptr(&fbuffer),
-                    O_CREAT | O_WRONLY | O_EXCL | CURL_O_BINARY, OPENMODE);
+          fd = curlx_open(curlx_dyn_ptr(&fbuffer),
+                          O_CREAT | O_WRONLY | O_EXCL | CURL_O_BINARY,
+                          OPENMODE);
           /* Keep retrying in the hope that it is not interrupted sometime */
         } while(fd == -1 && errno == EINTR);
       }

src/tool_doswin.c

@@ -532,7 +532,7 @@ static SANITIZEcode rename_if_reserved_dos(char **const sanitized,
      identify whether it is a reserved device name and not a regular
      filename. */
 #ifdef MSDOS
-  if(base && ((stat(base, &st_buf)) == 0) && (S_ISCHR(st_buf.st_mode))) {
+  if(base && (curlx_stat(base, &st_buf) == 0) && S_ISCHR(st_buf.st_mode)) {
     /* Prepend a '_' */
     size_t blen = strlen(base);
     if(blen) {

src/tool_filetime.c

@@ -75,7 +75,7 @@ int getfiletime(const char *filename, curl_off_t *stamp)
   }
 #else
   struct_stat statbuf;
-  if(stat(filename, &statbuf) != -1) {
+  if(curlx_stat(filename, &statbuf) != -1) {
     *stamp = (curl_off_t)statbuf.st_mtime;
     rc = 0;
   }

src/tool_findfile.c

@@ -33,10 +33,6 @@
 #endif
 #endif
 
-#ifdef HAVE_FCNTL_H
-#include <fcntl.h>
-#endif
-
 #include "tool_findfile.h"
 #include "tool_cfgable.h"
 
@@ -77,7 +73,7 @@ static char *checkhome(const char *home, const char *fname, bool dotscore)
     else
       c = aprintf("%s" DIR_CHAR "%s", home, fname);
     if(c) {
-      int fd = open(c, O_RDONLY);
+      int fd = curlx_open(c, O_RDONLY);
       if(fd >= 0) {
         char *path = strdup(c);
         close(fd);

src/tool_getpass.c

@@ -30,10 +30,6 @@
 #ifndef HAVE_GETPASS_R
 /* this file is only for systems without getpass_r() */
 
-#ifdef HAVE_FCNTL_H
-#  include <fcntl.h>
-#endif
-
 #ifdef HAVE_TERMIOS_H
 #  include <termios.h>
 #elif defined(HAVE_TERMIO_H)
@@ -178,7 +174,7 @@ char *getpass_r(const char *prompt, /* prompt to display */
 {
   ssize_t nread;
   bool disabled;
-  int fd = open("/dev/tty", O_RDONLY);
+  int fd = curlx_open("/dev/tty", O_RDONLY);
   if(fd == -1)
     fd = STDIN_FILENO; /* use stdin if the tty could not be used */
 

src/tool_operate.c

@@ -23,10 +23,6 @@
  ***************************************************************************/
 #include "tool_setup.h"
 
-#ifdef HAVE_FCNTL_H
-#  include <fcntl.h>
-#endif
-
 #ifdef HAVE_LOCALE_H
 #  include <locale.h>
 #endif
@@ -279,22 +275,22 @@ static CURLcode pre_transfer(struct per_transfer *per)
 #ifdef __VMS
     /* Calculate the real upload size for VMS */
     per->infd = -1;
-    if(stat(per->uploadfile, &fileinfo) == 0) {
+    if(curlx_stat(per->uploadfile, &fileinfo) == 0) {
       fileinfo.st_size = VmsSpecialSize(uploadfile, &fileinfo);
       switch(fileinfo.st_fab_rfm) {
       case FAB$C_VAR:
       case FAB$C_VFC:
       case FAB$C_STMCR:
-        per->infd = open(per->uploadfile, O_RDONLY | CURL_O_BINARY);
+        per->infd = curlx_open(per->uploadfile, O_RDONLY | CURL_O_BINARY);
         break;
       default:
-        per->infd = open(per->uploadfile, O_RDONLY | CURL_O_BINARY,
-                         "rfm=stmlf", "ctx=stm");
+        per->infd = curlx_open(per->uploadfile, O_RDONLY | CURL_O_BINARY,
+                               "rfm=stmlf", "ctx=stm");
       }
     }
     if(per->infd == -1)
 #else
-      per->infd = open(per->uploadfile, O_RDONLY | CURL_O_BINARY);
+      per->infd = curlx_open(per->uploadfile, O_RDONLY | CURL_O_BINARY);
     if((per->infd == -1) || fstat(per->infd, &fileinfo))
 #endif
     {
@@ -668,8 +664,7 @@ static CURLcode post_per_transfer(struct per_transfer *per,
     }
     if(result && config->rm_partial) {
       struct_stat st;
-      if(!stat(outs->filename, &st) &&
-         S_ISREG(st.st_mode)) {
+      if(!curlx_stat(outs->filename, &st) && S_ISREG(st.st_mode)) {
         if(!unlink(outs->filename))
           notef("Removed output file: %s", outs->filename);
         else
@@ -974,7 +969,7 @@ static CURLcode setup_outfile(struct OperationConfig *config,
 
   if(config->skip_existing) {
     struct_stat fileinfo;
-    if(!stat(per->outfile, &fileinfo)) {
+    if(!curlx_stat(per->outfile, &fileinfo)) {
       /* file is present */
       notef("skips transfer, \"%s\" exists locally", per->outfile);
       per->skip = TRUE;
@@ -987,7 +982,7 @@ static CURLcode setup_outfile(struct OperationConfig *config,
        of the file as it is now and open it for append instead */
     struct_stat fileinfo;
     /* VMS -- Danger, the filesize is only valid for stream files */
-    if(stat(per->outfile, &fileinfo) == 0)
+    if(curlx_stat(per->outfile, &fileinfo) == 0)
       /* set offset to current file size: */
       config->resume_from = fileinfo.st_size;
     else