added truncateFile.c

src/libCom/Makefile.Host

@@ -33,6 +33,7 @@ INC += sigPipeIgnore.h
 INC += dbmf.h
 INC += ipAddrToA.h
 INC += epicsString.h
+INC += truncateFile.h
 
 #	For WIN32 we supply getopt as part of libCom:
 INC_WIN32 := getopt.h
@@ -68,6 +69,7 @@ LIBSRCS += sigPipeIgnore.c
 LIBSRCS += dbmf.c
 LIBSRCS += ipAddrToA.c
 LIBSRCS += epicsString.c
+LIBSRCS += truncateFile.c
 
 #
 # if CPLUSPLUS isnt empty then include C++ src codes

src/libCom/misc/truncateFile.c

@@ -0,0 +1,120 @@
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+
+#define epicsExportSharedSymbols
+#include "truncateFile.h"
+
+#ifndef SEEK_END
+#define SEEK_END 2
+#endif
+
+/*
+ * truncate to specified size (we dont use truncate()
+ * because it is not portable)
+ */
+epicsShareFunc enum TF_RETURN  epicsShareAPI truncateFile (const char *pFileName, unsigned size)
+{
+	char tmpName[L_tmpnam];
+	long filePos;
+	char *pTmpFN;
+	FILE *pFile;
+	FILE *ptmp;
+	int status;
+	int c;
+	unsigned charNo;
+	
+	pFile = fopen(pFileName, "r");
+	if (!pFile) {
+		fprintf (stderr,
+			"File access problems to `%s' because `%s'\n", 
+			pFileName,
+			strerror(errno));
+		return TF_ERROR;
+	}
+
+	/*
+	 * This is not required under UNIX but does appear
+	 * to be required under WIN32. 
+	 */
+	status = fseek (pFile, 0L, SEEK_END);
+	if (status!=TF_OK) {
+		fclose (pFile);
+		return TF_ERROR;
+	}
+
+	filePos = ftell(pFile);
+	if (filePos <= size) {
+		fclose (pFile);
+		return TF_OK;
+	}
+
+	pTmpFN = tmpnam (tmpName);
+	if (!pTmpFN) {
+		fprintf (stderr,"Unable to create tmp file name?\n");
+		fclose (pFile);
+		return TF_ERROR;
+	}
+
+	ptmp = fopen (pTmpFN, "w");
+	if (!ptmp) {
+		fprintf (stderr,
+			"File access problems to `%s' because `%s'\n", 
+			pTmpFN,
+			strerror(errno));
+		fclose (pFile);
+		return TF_ERROR;
+	}
+	rewind (pFile);
+	charNo = 0u;
+	while (charNo<size) {
+		c = getc (pFile);
+		if (c==EOF) {
+			fprintf (stderr,
+				"File access problems to `%s' because `%s'\n", 
+				pFileName,
+				strerror(errno));
+			fclose (pFile);
+			fclose (ptmp);
+			remove (pTmpFN);
+			return TF_ERROR;
+		}
+		status = putc (c, ptmp);
+		if (status==EOF) {
+			fprintf(stderr,
+				"File access problems to `%s' because `%s'\n", 
+				pTmpFN,
+				strerror(errno));
+			fclose (pFile);
+			fclose (ptmp);
+			remove (pTmpFN);
+			return TF_ERROR;
+		}
+		charNo++;
+	}
+	fclose (pFile);
+	fclose (ptmp);
+	status = remove (pFileName);
+	if (status!=TF_OK) {
+		fprintf (stderr,
+			"Unable to remove `%s' during truncate because `%s'\n", 
+			pFileName,
+			strerror(errno));
+		remove (pTmpFN);
+		return TF_ERROR;
+	}
+	status = rename (pTmpFN, pFileName);
+	if (status!=TF_OK) {
+		fprintf (stderr,
+			"Unable to rename %s to `%s' because `%s'\n", 
+			pTmpFN,
+			pFileName,
+			strerror(errno));
+		remove (pTmpFN);
+		return TF_ERROR;
+	}
+	return TF_OK;
+}
+

src/libCom/misc/truncateFile.h

@@ -0,0 +1,17 @@
+
+#include "shareLib.h"
+
+/*
+ * truncate to specified size (we dont use truncate()
+ * because it is not portable)
+ *
+ * pFileName - name (and optionally path) of file
+ * size - the new file size (if file is curretly larger)
+ * 
+ * returns TF_OK if the file is less than size bytes
+ * or if it was successfully truncated. Returns
+ * TF_ERROR if the file could not be truncated.
+ */
+enum TF_RETURN {TF_OK=0, TF_ERROR=1};
+epicsShareFunc enum TF_RETURN epicsShareAPI truncateFile (const char *pFileName, unsigned size);
+

src/libCom/truncateFile.c

@@ -0,0 +1,120 @@
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+
+#define epicsExportSharedSymbols
+#include "truncateFile.h"
+
+#ifndef SEEK_END
+#define SEEK_END 2
+#endif
+
+/*
+ * truncate to specified size (we dont use truncate()
+ * because it is not portable)
+ */
+epicsShareFunc enum TF_RETURN  epicsShareAPI truncateFile (const char *pFileName, unsigned size)
+{
+	char tmpName[L_tmpnam];
+	long filePos;
+	char *pTmpFN;
+	FILE *pFile;
+	FILE *ptmp;
+	int status;
+	int c;
+	unsigned charNo;
+	
+	pFile = fopen(pFileName, "r");
+	if (!pFile) {
+		fprintf (stderr,
+			"File access problems to `%s' because `%s'\n", 
+			pFileName,
+			strerror(errno));
+		return TF_ERROR;
+	}
+
+	/*
+	 * This is not required under UNIX but does appear
+	 * to be required under WIN32. 
+	 */
+	status = fseek (pFile, 0L, SEEK_END);
+	if (status!=TF_OK) {
+		fclose (pFile);
+		return TF_ERROR;
+	}
+
+	filePos = ftell(pFile);
+	if (filePos <= size) {
+		fclose (pFile);
+		return TF_OK;
+	}
+
+	pTmpFN = tmpnam (tmpName);
+	if (!pTmpFN) {
+		fprintf (stderr,"Unable to create tmp file name?\n");
+		fclose (pFile);
+		return TF_ERROR;
+	}
+
+	ptmp = fopen (pTmpFN, "w");
+	if (!ptmp) {
+		fprintf (stderr,
+			"File access problems to `%s' because `%s'\n", 
+			pTmpFN,
+			strerror(errno));
+		fclose (pFile);
+		return TF_ERROR;
+	}
+	rewind (pFile);
+	charNo = 0u;
+	while (charNo<size) {
+		c = getc (pFile);
+		if (c==EOF) {
+			fprintf (stderr,
+				"File access problems to `%s' because `%s'\n", 
+				pFileName,
+				strerror(errno));
+			fclose (pFile);
+			fclose (ptmp);
+			remove (pTmpFN);
+			return TF_ERROR;
+		}
+		status = putc (c, ptmp);
+		if (status==EOF) {
+			fprintf(stderr,
+				"File access problems to `%s' because `%s'\n", 
+				pTmpFN,
+				strerror(errno));
+			fclose (pFile);
+			fclose (ptmp);
+			remove (pTmpFN);
+			return TF_ERROR;
+		}
+		charNo++;
+	}
+	fclose (pFile);
+	fclose (ptmp);
+	status = remove (pFileName);
+	if (status!=TF_OK) {
+		fprintf (stderr,
+			"Unable to remove `%s' during truncate because `%s'\n", 
+			pFileName,
+			strerror(errno));
+		remove (pTmpFN);
+		return TF_ERROR;
+	}
+	status = rename (pTmpFN, pFileName);
+	if (status!=TF_OK) {
+		fprintf (stderr,
+			"Unable to rename %s to `%s' because `%s'\n", 
+			pTmpFN,
+			pFileName,
+			strerror(errno));
+		remove (pTmpFN);
+		return TF_ERROR;
+	}
+	return TF_OK;
+}
+

src/libCom/truncateFile.h

@@ -0,0 +1,17 @@
+
+#include "shareLib.h"
+
+/*
+ * truncate to specified size (we dont use truncate()
+ * because it is not portable)
+ *
+ * pFileName - name (and optionally path) of file
+ * size - the new file size (if file is curretly larger)
+ * 
+ * returns TF_OK if the file is less than size bytes
+ * or if it was successfully truncated. Returns
+ * TF_ERROR if the file could not be truncated.
+ */
+enum TF_RETURN {TF_OK=0, TF_ERROR=1};
+epicsShareFunc enum TF_RETURN epicsShareAPI truncateFile (const char *pFileName, unsigned size);
+