add zsv_fopen_wx to util/file; use exclusive write for zvs_file_copy (#…

…173)

fix configure/Makefile to work for compilers that do not work with -static

app/Makefile

@@ -175,7 +175,7 @@ CFLAGS+= -DUSE_JQ
 
 STATIC_LIB_FLAGS=
 ifneq ($(STATIC_LIBS),)
-  STATIC_LIB_FLAGS=-static ${STATIC_LIBS}
+  STATIC_LIB_FLAGS=${LDFLAGS_STATIC}
 endif
 
 STANDALONE_PFX=${BUILD_DIR}/bin/zsv_

app/utils/file.c

@@ -119,6 +119,28 @@ int zsv_file_exists(const char* filename) {
 }
 #endif
 
+/**
+ * Open a file for exclusive write (same as fopen() but opens exclusively)
+ * mode must be 'w' or 'wb'
+ */
+FILE* zsv_fopen_wx(const char *filename, const char *mode) {
+  if(!mode || (strcmp(mode, "w") && strcmp(mode, "wb"))) {
+    fprintf(stderr, "fopen_wbx mode must be 'w' or 'wb'; got %s\n", mode ? mode : "(none)");
+    return NULL;
+  }
+
+  int fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0644); // exclusive binary write
+  if(fd == -1) {
+    return NULL;
+  }
+
+  FILE *file = fdopen(fd, "wb"); // Convert to FILE*
+  if(file == NULL)
+    close(fd);
+
+  return file;
+}
+
 /**
  * Copy a file, given source and destination paths
  * On error, output error message and return non-zero
@@ -133,16 +155,22 @@ int zsv_copy_file(const char *src, const char *dest) {
   // copy the file
   int err = 0;
   FILE *fsrc = fopen(src, "rb");
-  if(!fsrc)
-    err = errno ? errno : -1, perror(src);
-  else {
-    FILE *fdest = fopen(dest, "wb");
-    if(!fdest)
-      err = errno ? errno : -1, perror(dest);
-    else {
+  if(!fsrc) {
+    err = errno ? errno : -1;
+    perror(src);
+  } else {
+    FILE *fdest = zsv_fopen_wx(dest, "wb");
+    if(!fdest) {
+      err = errno ? errno : -1;
+      perror(dest);
+    } else {
       err = zsv_copy_file_ptr(fsrc, fdest);
-      if(err)
-        perror(dest);
+      if(err) {
+        if(err < 0)
+          fprintf(stderr, "Unknown error copying %s to %s\n", src, dest);
+        else
+          perror(dest);
+      }
       fclose(fdest);
     }
     fclose(fsrc);
@@ -155,16 +183,14 @@ int zsv_copy_file(const char *src, const char *dest) {
  * Return error number per errno.h
  */
 int zsv_copy_file_ptr(FILE *src, FILE *dest) {
-  int err = 0;
+  errno = 0;
   char buffer[4096];
   size_t bytes_read;
   while((bytes_read = fread(buffer, 1, sizeof(buffer), src)) > 0) {
-    if(fwrite(buffer, 1, bytes_read, dest) != bytes_read) {
-      err = errno ? errno : -1;
-      break;
-    }
+    if(fwrite(buffer, 1, bytes_read, dest) != bytes_read)
+      return errno ? errno : -1;
   }
-  return err;
+  return errno;
 }
 
 size_t zsv_dir_len_basename(const char *filepath, const char **basename) {

configure

@@ -466,6 +466,7 @@ _ACEOF
 tryflag   CFLAGS_TRY  -Werror=unknown-warning-option
 tryflag   CFLAGS_TRY  -Werror=unused-command-line-argument
 tryflag   CFLAGS_TRY  -Werror=ignored-optimization-argument
+tryldflag LDFLAGS_STATIC -static
 tryldflag LDFLAGS_TRY -Werror=unknown-warning-option
 tryldflag LDFLAGS_TRY -Werror=unused-command-line-argument
 tryldflag LDFLAGS_TRY -Werror=ignored-optimization-argument
@@ -729,6 +730,7 @@ CFLAGS_PIC = $CFLAGS_PIC
 LDFLAGS_PIC = $LDFLAGS_PIC
 CFLAGS_PIE = $CFLAGS_PIE
 LDFLAGS_PIE = $LDFLAGS_PIE
+LDFLAGS_STATIC = $LDFLAGS_STATIC
 USE_DEBUG_STDERR = $USE_DEBUG_STDERR
 CFLAGS_VECTORIZE = $CFLAGS_VECTORIZE
 CFLAGS_VECTORIZE_OPTIMIZED = $CFLAGS_VECTORIZE_OPTIMIZED

include/zsv/utils/file.h

@@ -61,6 +61,12 @@ size_t zsv_filter_write(void *FILEp, unsigned char *buff, size_t bytes_read);
  */
 size_t zsv_dir_len_basename(const char *filepath, const char **basename);
 
+/**
+ * Open a file for exclusive write (same as fopen() but opens exclusively)
+ * mode must be 'w' or 'wb'
+ */
+FILE* zsv_fopen_wx(const char *filename, const char *mode);
+
 /**
  * Copy a file. Create any needed directories
  * On error, prints error message and returns non-zero