diff: fix bug 613 (diff -ub segfaults)

function                                             old     new   delta
dump_unified_vec                                     435     457     +22
diff_main                                            855     860      +5
diffreg                                             1786    1781      -5
do_diff                                              428     416     -12
change                                               325     283     -42
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/3 up/down: 27/-59)            Total: -32 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/editors/diff.c b/editors/diff.c
index e3933e72424cc22ada27a9a76227e10e0431ac60..42aba9ae0e29a8b0835cf14acd29dfe0354c54ad 100644 (file)
--- a/editors/diff.c
+++ b/editors/diff.c
@@ -102,7 +102,7 @@ struct globals {
        bool anychange;
        smallint exit_status;
        int opt_U_context;
-       size_t max_context;     /* size of context_vec_start */
+       int context_idx;
        IF_FEATURE_DIFF_DIR(int dl_count;)
        IF_FEATURE_DIFF_DIR(char **dl;)
        char *opt_S_start;
@@ -119,9 +119,7 @@ struct globals {
        long *ixold;            /* will be overlaid on klist */
        struct line *nfile[2];
        struct line *sfile[2];  /* shortened by pruning common prefix/suffix */
-       struct context_vec *context_vec_start;
-       struct context_vec *context_vec_end;
-       struct context_vec *context_vec_ptr;
+       struct context_vec *context_vector;
        char *tempname1, *tempname2;
        struct stat stb1, stb2;
 };
@@ -129,7 +127,7 @@ struct globals {
 #define anychange          (G.anychange         )
 #define exit_status        (G.exit_status       )
 #define opt_U_context      (G.opt_U_context     )
-#define max_context        (G.max_context       )
+#define context_idx        (G.context_idx       )
 #define dl_count           (G.dl_count          )
 #define dl                 (G.dl                )
 #define opt_S_start        (G.opt_S_start       )
@@ -147,9 +145,7 @@ struct globals {
 #define ixold              (G.ixold             )
 #define nfile              (G.nfile             )
 #define sfile              (G.sfile             )
-#define context_vec_start  (G.context_vec_start )
-#define context_vec_end    (G.context_vec_end   )
-#define context_vec_ptr    (G.context_vec_ptr   )
+#define context_vector     (G.context_vector    )
 #define stb1               (G.stb1              )
 #define stb2               (G.stb2              )
 #define tempname1          (G.tempname1         )
@@ -157,7 +153,7 @@ struct globals {
 #define INIT_G() do { \
        SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
        opt_U_context = 3; \
-       max_context = 64; \
+       context_vector = xrealloc_vector(context_vector, 6, 0); \
 } while (0)
 
 
@@ -230,11 +226,10 @@ static ALWAYS_INLINE int fiddle_sum(int sum, int t)
 }
 static int readhash(FILE *fp)
 {
-       int i, t, space;
+       int i, t;
        int sum;
 
        sum = 1;
-       space = 0;
        i = 0;
        if (!(option_mask32 & (FLAG_b | FLAG_w))) {
                while ((t = getc(fp)) != '\n') {
@@ -247,8 +242,11 @@ static int readhash(FILE *fp)
                        i = 1;
                }
        } else {
+               int space = 0;
+
                while (1) {
-                       switch (t = getc(fp)) {
+                       t = getc(fp);
+                       switch (t) {
                        case '\t':
                        case '\r':
                        case '\v':
@@ -763,19 +761,19 @@ static int asciifile(FILE *f)
 /* dump accumulated "unified" diff changes */
 static void dump_unified_vec(FILE *f1, FILE *f2)
 {
-       struct context_vec *cvp = context_vec_start;
+       struct context_vec *cvp = context_vector;
        int lowa, upb, lowc, upd;
        int a, b, c, d;
        char ch;
 
-       if (context_vec_start > context_vec_ptr)
+       if (context_idx < 0)
                return;
 
        b = d = 0;                      /* gcc */
        lowa = MAX(1, cvp->a - opt_U_context);
-       upb = MIN(nlen[0], context_vec_ptr->b + opt_U_context);
+       upb = MIN(nlen[0], context_vector[context_idx].b + opt_U_context);
        lowc = MAX(1, cvp->c - opt_U_context);
-       upd = MIN(nlen[1], context_vec_ptr->d + opt_U_context);
+       upd = MIN(nlen[1], context_vector[context_idx].d + opt_U_context);
 
        printf("@@ -");
        uni_range(lowa, upb);
@@ -787,7 +785,7 @@ static void dump_unified_vec(FILE *f1, FILE *f2)
         * Output changes in "unified" diff format--the old and new lines
         * are printed together.
         */
-       for (; cvp <= context_vec_ptr; cvp++) {
+       for (; cvp <= &context_vector[context_idx]; cvp++) {
                a = cvp->a;
                b = cvp->b;
                c = cvp->c;
@@ -834,7 +832,7 @@ static void dump_unified_vec(FILE *f1, FILE *f2)
        }
        fetch(ixnew, d + 1, upd, f2, ' ');
 
-       context_vec_ptr = context_vec_start - 1;
+       context_idx = -1;
 }
 
 
@@ -866,25 +864,13 @@ static void change(const char *file1, FILE *f1, const char *file2, FILE *f2,
                return;
        }
 
-       /*
-        * Allocate change records as needed.
-        */
-       if (context_vec_ptr == context_vec_end - 1) {
-               ptrdiff_t offset = context_vec_ptr - context_vec_start;
-
-               max_context <<= 1;
-               context_vec_start = xrealloc(context_vec_start,
-                               max_context * sizeof(struct context_vec));
-               context_vec_end = context_vec_start + max_context;
-               context_vec_ptr = context_vec_start + offset;
-       }
        if (anychange == 0) {
                /*
                 * Print the context/unidiff header first time through.
                 */
                print_header(file1, file2);
-       } else if (a > context_vec_ptr->b + (2 * opt_U_context) + 1
-               && c > context_vec_ptr->d + (2 * opt_U_context) + 1
+       } else if (a > context_vector[context_idx].b + (2 * opt_U_context) + 1
+               && c > context_vector[context_idx].d + (2 * opt_U_context) + 1
        ) {
                /*
                 * If this change is more than 'context' lines from the
@@ -893,11 +879,12 @@ static void change(const char *file1, FILE *f1, const char *file2, FILE *f2,
 // dump_unified_vec() seeks!
                dump_unified_vec(f1, f2);
        }
-       context_vec_ptr++;
-       context_vec_ptr->a = a;
-       context_vec_ptr->b = b;
-       context_vec_ptr->c = c;
-       context_vec_ptr->d = d;
+       context_idx++;
+       context_vector = xrealloc_vector(context_vector, 6, context_idx);
+       context_vector[context_idx].a = a;
+       context_vector[context_idx].b = b;
+       context_vector[context_idx].c = c;
+       context_vector[context_idx].d = d;
        anychange = 1;
 }
 
@@ -1010,7 +997,7 @@ static unsigned diffreg(const char *file1, const char *file2, int flags)
        int i;
 
        anychange = 0;
-       context_vec_ptr = context_vec_start - 1;
+       context_idx = -1;
        tempname1 = tempname2 = NULL;
 
        /* Is any of them a directory? Then it's simple */