sadc: Append data only to strictly compliant files

The rule is that sar/sadc should only append data to datafile whose
format is strictly that expected by current sysstat version.

Signed-off-by: Sebastien GODARD <sysstat@users.noreply.github.com>

diff --git a/sadc.c b/sadc.c
index 2c97b05fea48ef80b1524b118a8402d77c2afbee..e58dac9c9436abbab9ca59238fb06df7538cc5de 100644 (file)
--- a/sadc.c
+++ b/sadc.c
@@ -724,8 +724,6 @@ void write_stats(int ofd)
  */
 void rewrite_file_hdr(int *ofd, off_t fpos, struct file_magic *file_magic)
 {
-       int n;
-
        /* Remove O_APPEND status flag */
        if (fcntl(*ofd, F_SETFL, 0) < 0) {
                perror("fcntl");
@@ -738,8 +736,7 @@ void rewrite_file_hdr(int *ofd, off_t fpos, struct file_magic *file_magic)
                exit(2);
        }
 
-       n = MINIMUM(file_magic->header_size, FILE_HEADER_SIZE);
-       if (write_all(*ofd, &file_hdr, n) != n) {
+       if (write_all(*ofd, &file_hdr, FILE_HEADER_SIZE) != FILE_HEADER_SIZE) {
                p_write_error();
        }
 
@@ -810,6 +807,8 @@ void open_stdout(int *stdfd)
  ***************************************************************************
  * Get descriptor for output file and write its header.
  * We may enter this function several times (when we rotate a file).
+ * NB: If data are appended to an existing file then the format must be
+ * strictly that expected by current version.
  *
  * IN:
  * @ofile              Name of output file.
@@ -826,8 +825,7 @@ void open_ofile(int *ofd, char ofile[], int restart_mark)
        struct file_magic file_magic;
        struct file_activity file_act[NR_ACT];
        struct tm rectime = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, NULL};
-       void *buffer = NULL;
-       ssize_t sz, n;
+       ssize_t sz;
        off_t fpos;
        int i, j, p;
 
@@ -856,7 +854,7 @@ void open_ofile(int *ofd, char ofile[], int restart_mark)
        if ((sz != FILE_MAGIC_SIZE) ||
            (file_magic.sysstat_magic != SYSSTAT_MAGIC) ||
            (file_magic.format_magic != FORMAT_MAGIC) ||
-           (file_magic.header_size > MAX_FILE_HEADER_SIZE)) {
+           (file_magic.header_size != FILE_HEADER_SIZE)) {
                if (FORCE_FILE(flags)) {
                        close(*ofd);
                        /* -F option used: Truncate file */
@@ -867,8 +865,6 @@ void open_ofile(int *ofd, char ofile[], int restart_mark)
                handle_invalid_sa_file(ofd, &file_magic, ofile, sz);
        }
 
-       SREALLOC(buffer, char, file_magic.header_size);
-
        /*
         * Save current file position.
         * Needed later to update sa_last_cpu_nr.
@@ -879,14 +875,8 @@ void open_ofile(int *ofd, char ofile[], int restart_mark)
        }
 
        /* Read file standard header */
-       n = read(*ofd, buffer, file_magic.header_size);
-       memcpy(&file_hdr, buffer, MINIMUM(file_magic.header_size, FILE_HEADER_SIZE));
-       free(buffer);
-
-       if (n != file_magic.header_size) {
-               /* Display error message and exit */
-               handle_invalid_sa_file(ofd, &file_magic, ofile, 0);
-       }
+       if ((sz = read(*ofd, &file_hdr, FILE_HEADER_SIZE)) != FILE_HEADER_SIZE)
+               goto append_error;
 
        /*
         * If we are using the standard daily data file (file specified