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Merge pull request #451 from rednex/atomic_output

Make RGBASM overwrite output files atomically

--- a/src/asm/output.c

+++ b/src/asm/output.c

@@ -16,7 +16,24 @@

 #include <stdint.h>

 #include <stdlib.h>

 #include <string.h>

+#include <unistd.h>

+#include <libgen.h>

+#ifdef _WIN32

+#include <windows.h>

+#include <winbase.h>

+/*

+ * The semantics of `rename` on Windows differ from POSIX in that it errors out

+ * when the target file exists, instead of overwriting it.

+ * Thus, shim `rename` with similar semantics (note that the return value of

+ * `MoveFileExA` is inverted, and it uses `GetLastError` instead of `errno`)

+ */

+#define rename(oldname, newname) \

+	MoveFileExA(oldname, newname, MOVEFILE_WRITE_THROUGH | \

+				      MOVEFILE_REPLACE_EXISTING) \

+	? 0 : (errno = GetLastError(), -1)

+#endif

+

 #include "asm/asm.h"

 #include "asm/charmap.h"

 #include "asm/fstack.h"

@@ -531,13 +548,25 @@

  */

 void out_WriteObject(void)

 {

+	/* Write to a temporary file in the target's folder */

+	char *objectNameCopy = strdup(tzObjectname);

+	char const *dirPath = dirname(objectNameCopy);

+	char tmpFileName[strlen(dirPath) + 1 + 16 + 1];

+

+	sprintf(tmpFileName, "%s/rgbasm_tmpXXXXXX", dirPath);

+	free(objectNameCopy);

+	int fd = mkstemp(tmpFileName);

+

 	FILE *f;

 	struct PatchSymbol *pSym;

 	struct Section *pSect;

+	if (fd == -1)

+		err(1, "Couldn't create temporary file");

+

 	addexports();

-	f = fopen(tzObjectname, "wb");

+	f = fdopen(fd, "wb");

 	if (f == NULL)

 		fatalerror("Couldn't write file '%s'\n", tzObjectname);

@@ -560,6 +589,11 @@

 	}

 	fclose(f);

+	close(fd);

+

+	if (rename(tmpFileName, tzObjectname) != 0)

+		err(1, "Couldn't create object file (temp file kept as %s)",

+		    tmpFileName);

 }

 /*