top: with lib xalloc changes, restored prior memory logic

With the privatization of the library xalloc functions,
this patch restores top's previous internal memory logic.

This puts us back on a 3.3.1 (and earlier) footing wherein
memory allocation errors carry these implications:
  . if top detected, the terminal will be restored
    prior to an abnormal exit and message
  . if library detected, the terminal will become
    corrupted following the message

To my knowledge, neither type of memory error has ever occurred
during the nine years since top was rewritten.  So the issue of
restoring the termios structure is probably moot.

2 files changed, 39 insertions, 12 deletions

diff --git a/top.c b/top.c
index 1ccb7a1..76ef9e1 100644
--- a/top.c
+++ b/top.c
@@ -487,7 +487,7 @@ static void error_exit (const char *str) {
 
 
         /*
-         * Handle library memory errors ourselves rather than accept a default
+         * Handle library errors ourselves rather than accept a default
          * fprintf to stderr (since we've mucked with the termios struct) */
 static void library_err (const char *fmts, ...) NORETURN;
 static void library_err (const char *fmts, ...) {
@@ -789,7 +789,33 @@ static void show_special (int interact, const char *glob) {
    if (*glob) PUTT("%.*s", Screen_cols -1, glob);
 } // end: show_special
 
-/*######  Low Level Keyboard support  ####################################*/
+/*######  Low Level Memory/Keyboard support  #############################*/
+
+        /*
+         * Handle our own memory stuff without the risk of leaving the
+         * user's terminal in an ugly state should things go sour. */
+
+static void *alloc_c (size_t num) MALLOC;
+static void *alloc_c (size_t num) {
+   void *pv;
+
+   if (!num) ++num;
+   if (!(pv = calloc(1, num)))
+      error_exit("failed memory allocate");
+   return pv;
+} // end: alloc_c
+
+
+static void *alloc_r (void *ptr, size_t num) MALLOC;
+static void *alloc_r (void *ptr, size_t num) {
+   void *pv;
+
+   if (!num) ++num;
+   if (!(pv = realloc(ptr, num)))
+      error_exit("failed memory re-allocate");
+   return pv;
+} // end: alloc_r
+
 
         /*
          * This routine isolates ALL user INPUT and ensures that we
@@ -1318,7 +1344,7 @@ static void adj_geometry (void) {
    // we'll only grow our Pseudo_screen, never shrink it
    if (pseudo_max < Pseudo_size) {
       pseudo_max = Pseudo_size;
-      Pseudo_screen = realloc(Pseudo_screen, pseudo_max);
+      Pseudo_screen = alloc_r(Pseudo_screen, pseudo_max);
    }
    PSU_CLREOS(0);
    if (Frames_resize) putp(Cap_clr_scr);
@@ -1768,8 +1794,7 @@ static CPU_t *cpus_refresh (CPU_t *cpus) {
       /* note: we allocate one more CPU_t than Cpu_tot so that the last slot
                can hold tics representing the /proc/stat cpu summary (the first
                line read) -- that slot supports our View_CPUSUM toggle */
-      if ((cpus = calloc((1 + Cpu_tot),sizeof(CPU_t)))==NULL)
-         error_exit(fmtmk("failed to allocate memory for CPU_t"));
+      cpus = alloc_c((1 + Cpu_tot) * sizeof(CPU_t));
    }
    rewind(fp);
    fflush(fp);
@@ -1920,8 +1945,8 @@ static void prochlp (proc_t *this) {
 
    if (Frame_maxtask+1 >= HHist_siz) {
       HHist_siz = HHist_siz * 5 / 4 + 100;
-      PHist_sav = realloc(PHist_sav, sizeof(HST_t) * HHist_siz);
-      PHist_new = realloc(PHist_new, sizeof(HST_t) * HHist_siz);
+      PHist_sav = alloc_r(PHist_sav, sizeof(HST_t) * HHist_siz);
+      PHist_new = alloc_r(PHist_new, sizeof(HST_t) * HHist_siz);
    }
 
    /* calculate time in this process; the sum of user time (utime) and
@@ -1971,7 +1996,7 @@ static void procs_refresh (void) {
    for (;;) {
       if (n_used == n_alloc) {
          n_alloc = 10 + ((n_alloc * 5) / 4);     // grow by over 25%
-         private_ppt = realloc(private_ppt, sizeof(proc_t*) * n_alloc);
+         private_ppt = alloc_r(private_ppt, sizeof(proc_t*) * n_alloc);
          // ensure NULL pointers for the additional memory just acquired
          memset(private_ppt + n_used, 0, sizeof(proc_t*) * (n_alloc - n_used));
       }
@@ -1990,7 +2015,7 @@ static void procs_refresh (void) {
    else {
       n_saved = n_alloc;
       for (i = 0; i < GROUPSMAX; i++) {
-         Winstk[i].ppt = realloc(Winstk[i].ppt, sizeof(proc_t*) * n_alloc);
+         Winstk[i].ppt = alloc_r(Winstk[i].ppt, sizeof(proc_t*) * n_alloc);
          memcpy(Winstk[i].ppt, private_ppt, sizeof(proc_t*) * n_used);
       }
    }
@@ -2035,7 +2060,7 @@ static void before (char *me) {
    struct sigaction sa;
    int i;
 
-   // setup our program name and library error message handler -- big!
+   // setup our program name -- big!
    Myname = strrchr(me, '/');
    if (Myname) ++Myname; else Myname = me;
 
@@ -3152,7 +3177,7 @@ static void forest_create (WIN_t *q) {
       qsort(Seed_ppt, Frame_maxtask, sizeof(proc_t*), Fieldstab[P_PPD].sort);
       if (hwmsav < Frame_maxtask) {         // grow, but never shrink
          hwmsav = Frame_maxtask;
-         Tree_ppt = realloc(Tree_ppt, sizeof(proc_t*) * hwmsav);
+         Tree_ppt = alloc_r(Tree_ppt, sizeof(proc_t*) * hwmsav);
       }
       while (0 == Seed_ppt[i]->ppid)        // identify trees (expect 2)
          forest_add(i++, 1);                // add parent plus children
diff --git a/top.h b/top.h
index a79286c..7c649d0 100644
--- a/top.h
+++ b/top.h
@@ -641,7 +641,9 @@ typedef struct WIN_t {
 //atic int           show_pmt (const char *str);
 //atic inline void   show_scroll (void);
 //atic void          show_special (int interact, const char *glob);
-/*------  Low Level Keyboard support  ------------------------------------*/
+/*------  Low Level Memory/Keyboard support  -----------------------------*/
+//atic void         *alloc_c (size_t num);
+//atic void         *alloc_r (void *ptr, size_t num);
 //atic int           chin (int ech, char *buf, unsigned cnt);
 //atic int           keyin (int init);
 //atic char         *linein (const char *prompt);