Fix -Wsign-compare compiler warnings (#2761)

db/drivers/dbf/table.c

@@ -58,7 +58,7 @@ int add_table(char *table, char *name)
 #else
     res = snprintf(db.tables[db.ntables].file, buf_s, "%s/%s", db.name, name);
 #endif
-    if (res >= buf_s) {
+    if (res < 0 || (size_t)res >= buf_s) {
         db_d_append_error(_("Unable to add table %s to %s. "
                             "The file path is too long."),
                           name, db.name);

display/d.legend/draw.c

@@ -283,7 +283,7 @@ void draw(const char *map_name, int maptype, int color, int thin, int lines,
             if (maxCat > 0.0) {
                 size_t b_s = sizeof(DispFormat);
                 int log_maxCat = (int)(log10(fabs(maxCat))) + 1;
-                if (snprintf(DispFormat, b_s, "%%%dd", log_maxCat) >= b_s)
+                if (snprintf(DispFormat, b_s, "%%%dd", log_maxCat) >= (int)b_s)
                     G_fatal_error(
                         _("Failed to create format string with maxCat=%f."),
                         maxCat);

display/d.linegraph/main.c

@@ -384,7 +384,7 @@ int main(int argc, char **argv)
 
     /* TODO: put this to variables, and avoid -Wsign-compare */
     for (i = 0; i < 3; i++) {
-        for (j = 0; j < strlen(title[i]->answer); j++)
+        for (j = 0; (size_t)j < strlen(title[i]->answer); j++)
             if (title[i]->answer[j] == '_')
                 title[i]->answer[j] = ' ';
     }
@@ -517,9 +517,9 @@ int main(int argc, char **argv)
     c = 0;
     j = 1;
     if (y_color_opt->answer != NULL) {
-        for (i = 0; i <= (strlen(y_color_opt->answer)); i++) {
+        for (i = 0; (size_t)i <= (strlen(y_color_opt->answer)); i++) {
             if ((y_color_opt->answer[i] == ',') ||
-                (i == (strlen(y_color_opt->answer)))) {
+                ((size_t)i == (strlen(y_color_opt->answer)))) {
                 color_name[c] = '\0';
                 in[j].color = D_translate_color(color_name);
                 j++;

display/d.mon/start.c

@@ -186,47 +186,47 @@ int start_mon(const char *name, const char *output, int select, int width,
     if (G_strncasecmp(name, "wx", 2) == 0) {
         sprintf(buf, "GRASS_RENDER_IMMEDIATE=default\n"); /* TODO: read settings
                                                              from wxGUI */
-        if (write(fd, buf, strlen(buf)) != strlen(buf))
+        if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
             G_fatal_error(_("Failed to write to file <%s>"), env_file);
         sprintf(buf, "GRASS_RENDER_FILE_READ=FALSE\n");
-        if (write(fd, buf, strlen(buf)) != strlen(buf))
+        if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
             G_fatal_error(_("Failed to write to file <%s>"), env_file);
         sprintf(buf, "GRASS_RENDER_TRANSPARENT=TRUE\n");
-        if (write(fd, buf, strlen(buf)) != strlen(buf))
+        if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
             G_fatal_error(_("Failed to write to file <%s>"), env_file);
     }
     else {
         sprintf(buf, "GRASS_RENDER_IMMEDIATE=%s\n", name);
-        if (write(fd, buf, strlen(buf)) != strlen(buf))
+        if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
             G_fatal_error(_("Failed to write to file <%s>"), env_file);
         sprintf(buf, "GRASS_RENDER_FILE_READ=TRUE\n");
-        if (write(fd, buf, strlen(buf)) != strlen(buf))
+        if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
             G_fatal_error(_("Failed to write to file <%s>"), env_file);
     }
     sprintf(buf, "GRASS_RENDER_FILE=%s\n", out_file);
-    if (write(fd, buf, strlen(buf)) != strlen(buf))
+    if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
         G_fatal_error(_("Failed to write to file <%s>"), env_file);
     sprintf(buf, "GRASS_RENDER_WIDTH=%d\n", width);
-    if (write(fd, buf, strlen(buf)) != strlen(buf))
+    if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
         G_fatal_error(_("Failed to write to file <%s>"), env_file);
     sprintf(buf, "GRASS_RENDER_HEIGHT=%d\n", height);
-    if (write(fd, buf, strlen(buf)) != strlen(buf))
+    if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
         G_fatal_error(_("Failed to write to file <%s>"), env_file);
     sprintf(buf, "GRASS_LEGEND_FILE=%s\n", leg_file);
-    if (write(fd, buf, strlen(buf)) != strlen(buf))
+    if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
         G_fatal_error(_("Failed to write to file <%s>"), env_file);
 
     if (bgcolor) {
         if (strcmp(bgcolor, "none") == 0)
             sprintf(buf, "GRASS_RENDER_TRANSPARENT=TRUE\n");
         else
             sprintf(buf, "GRASS_RENDER_BACKGROUNDCOLOR=%s\n", bgcolor);
-        if (write(fd, buf, strlen(buf)) != strlen(buf))
+        if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
             G_fatal_error(_("Failed to write to file <%s>"), env_file);
     }
     if (truecolor) {
         sprintf(buf, "GRASS_RENDER_TRUECOLOR=TRUE\n");
-        if (write(fd, buf, strlen(buf)) != strlen(buf))
+        if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
             G_fatal_error(_("Failed to write to file <%s>"), env_file);
     }
     close(fd);

general/g.mkfontcap/stroke_fonts.c

@@ -31,7 +31,7 @@ struct font_desc {
 };
 
 static struct font_desc *font_descriptions = NULL;
-static int num_descriptions = 0;
+static unsigned int num_descriptions = 0;
 
 static int load_font_descriptions(const char *);
 static void free_font_descriptions(void);
@@ -160,7 +160,7 @@ static int load_font_descriptions(const char *descfile)
 
 static const char *get_desc(const char *filename)
 {
-    int i;
+    unsigned int i;
 
     for (i = 0; i < num_descriptions; i++)
         if (G_strcasecmp(filename, font_descriptions[i].filename) == 0)
@@ -179,7 +179,7 @@ static const char *get_desc(const char *filename)
 
 static void free_font_descriptions(void)
 {
-    int i;
+    unsigned int i;
 
     for (i = 0; i < num_descriptions; i++) {
         G_free(font_descriptions[i].filename);

imagery/i.zc/main.c

@@ -35,11 +35,11 @@ int main(int argc, char *argv[])
     CELL *cell_row;
     float Width;
 
-    size_t i, j;    /* Loop control variables */
-    int or, oc;     /* Original dimensions of image */
-    int rows, cols; /* Smallest powers of 2 >= number of rows & columns */
-    size_t size;    /* the length of one side */
-    size_t totsize; /* the Total number of data points */
+    size_t i, j;         /* Loop control variables */
+    unsigned int or, oc; /* Original dimensions of image */
+    int rows, cols;      /* Smallest powers of 2 >= number of rows & columns */
+    size_t size;         /* the length of one side */
+    size_t totsize;      /* the Total number of data points */
     double
         *data[2]; /* Data structure containing real & complex values of FFT */
     struct GModule *module;

lib/cairodriver/read_bmp.c

@@ -46,7 +46,7 @@ static int read_bmp_header(const unsigned char *p)
     if (*p++ != 'M')
         return 0;
 
-    if (get_4(&p) != HEADER_SIZE + ca.width * ca.height * 4)
+    if (get_4(&p) != (unsigned int)HEADER_SIZE + ca.width * ca.height * 4)
         return 0;
 
     get_4(&p);
@@ -57,9 +57,9 @@ static int read_bmp_header(const unsigned char *p)
     if (get_4(&p) != 40)
         return 0;
 
-    if (get_4(&p) != ca.width)
+    if (get_4(&p) != (unsigned int)ca.width)
         return 0;
-    if (get_4(&p) != -ca.height)
+    if (get_4(&p) != (unsigned int)-ca.height)
         return 0;
 
     get_2(&p);
@@ -68,7 +68,7 @@ static int read_bmp_header(const unsigned char *p)
 
     if (get_4(&p) != 0)
         return 0;
-    if (get_4(&p) != ca.width * ca.height * 4)
+    if (get_4(&p) != (unsigned int)ca.width * ca.height * 4)
         return 0;
 
     get_4(&p);
@@ -94,7 +94,8 @@ void cairo_read_bmp(void)
     if (!read_bmp_header(header))
         G_fatal_error(_("Cairo: Invalid BMP header for <%s>"), ca.file_name);
 
-    if (fread(ca.grid, ca.stride, ca.height, input) != ca.height) {
+    if (fread(ca.grid, ca.stride, ca.height, input) !=
+        (unsigned int)ca.height) {
         if (feof(input))
             G_fatal_error(_("Cairo: error reading BMP file <%s>: "
                             "unexpected end of file"),

lib/calc/xrand.c

@@ -35,7 +35,7 @@ int f_rand(int argc, const int *argt, void **args)
                 lo = hi;
                 hi = tmp;
             }
-            res[i] = (lo == hi) ? lo : lo + x % (unsigned int)(hi - lo);
+            res[i] = (lo == hi) ? lo : (int)(lo + x % (unsigned int)(hi - lo));
         }
         return 0;
     }

lib/db/dbmi_driver/d_error.c

@@ -75,7 +75,7 @@ void db_d_append_error(const char *fmt, ...)
         count = vfprintf(fp, fmt, ap);
         if (count >= 0 && (work = G_calloc(count + 1, 1))) {
             rewind(fp);
-            if (fread(work, 1, count, fp) != count) {
+            if (fread(work, 1, count, fp) != (size_t)count) {
                 if (ferror(fp))
                     G_fatal_error(_("DBMI-%s driver file reading error: %s"),
                                   st->driver_name, strerror(errno));

lib/driver/font2.c

@@ -68,8 +68,8 @@ static void read_hersh(const char *filename)
         char buf[8];
         struct glyph *glyph;
         int coords;
-        unsigned int idx, count;
-        int c, i;
+        unsigned int i, idx, count;
+        int c;
 
         switch (c = fgetc(fp)) {
         case '\r':

lib/dspf/dspf_header.c

@@ -41,7 +41,8 @@ int dfwrite_header(file_info *headp)
     if (1 != fwrite(&linep->nthres, isize, 1, fp))
         return (-1);
     /* write the array of thresholds out */
-    if ((fwrite(linep->tvalue, flsize, linep->nthres, fp)) != linep->nthres) {
+    if ((fwrite(linep->tvalue, flsize, linep->nthres, fp)) !=
+        (size_t)linep->nthres) {
         fprintf(stderr, "ERROR: fwrite in dspf_header.c\n");
         return (-1);
     }

lib/gis/asprintf.c

@@ -113,7 +113,7 @@ int G_rasprintf(char **out, size_t *size, const char *fmt, ...)
         va_start(ap, fmt);
         count = vsnprintf(buf, osize, fmt, ap);
         va_end(ap);
-        if (count >= 0 && count < osize)
+        if (count >= 0 && (size_t)count < osize)
             break;
         if (count > -1)
             osize = count + 1;

lib/gis/cmprbzip.c

@@ -86,8 +86,8 @@ int G_bz2_compress(unsigned char *src, int src_sz, unsigned char *dst,
                    int dst_sz)
 {
     int err;
-    int i, buf_sz;
-    unsigned int nbytes;
+    int buf_sz;
+    unsigned int i, nbytes;
     unsigned char *buf;
 
 #ifndef HAVE_BZLIB_H
@@ -212,7 +212,7 @@ int G_bz2_expand(unsigned char *src, int src_sz, unsigned char *dst, int dst_sz)
      * updated buffer size
      */
 
-    if (nbytes != dst_sz) {
+    if (dst_sz < 0 || nbytes != (unsigned int)dst_sz) {
         /* TODO: it is not an error if destination is larger than needed */
         G_warning(_("Got uncompressed size %d, expected %d"), (int)nbytes,
                   dst_sz);

lib/gis/cmprzlib.c

@@ -1,5 +1,4 @@
-/*
- ****************************************************************************
+/*****************************************************************************
  *                     -- GRASS Development Team --
  *
  * MODULE:      GRASS gis library
@@ -116,7 +115,7 @@ int G_zlib_compress(unsigned char *src, int src_sz, unsigned char *dst,
     /* Output buffer should be large enough for single pass compression */
     buf = dst;
     buf_sz = G_zlib_compress_bound(src_sz);
-    if (buf_sz > dst_sz) {
+    if (dst_sz < 0 || buf_sz > (unsigned int)dst_sz) {
         G_warning(
             "G_zlib_compress(): programmer error, destination is too small");
         if (NULL ==
@@ -145,7 +144,7 @@ int G_zlib_compress(unsigned char *src, int src_sz, unsigned char *dst,
     }
 
     /* updated buf_sz is bytes of compressed data */
-    if (nbytes >= src_sz) {
+    if (src_sz < 0 || nbytes >= (unsigned int)src_sz) {
         /* compression not possible */
         if (buf != dst)
             G_free(buf);
@@ -205,7 +204,7 @@ int G_zlib_expand(unsigned char *src, int src_sz, unsigned char *dst,
      * updated buffer size
      */
 
-    if (nbytes != dst_sz) {
+    if (dst_sz < 0 || nbytes != (unsigned int)dst_sz) {
         /* TODO: it is not an error if destination is larger than needed */
         G_warning(_("Got uncompressed size %d, expected %d"), (int)nbytes,
                   dst_sz);

lib/gis/ls.c

@@ -183,7 +183,7 @@ void G_ls_format(char **list, int num_items, int perline, FILE *stream)
 #endif
 
     if (perline == 0) {
-        int max_len = 0;
+        unsigned int max_len = 0;
 
         for (i = 0; i < num_items; i++) {
             /* Find maximum filename length */

lib/gis/parser_dependencies.c

@@ -498,8 +498,11 @@ void G__describe_option_rules_xml(FILE *fp)
     for (i = 0; i < rules.count; i++) {
         const struct rule *rule = &((const struct rule *)rules.data)[i];
 
+        if (rule->count < 0)
+            G_fatal_error(_("Internal error: the number of options is < 0"));
+
         fprintf(fp, "\t\t<rule type=\"%s\">\n", rule_types[rule->type]);
-        for (j = 0; j < rule->count; j++) {
+        for (j = 0; j < (unsigned int)rule->count; j++) {
             void *p = rule->opts[j];
 
             if (is_flag(p)) {

lib/gis/snprintf.c

@@ -49,7 +49,7 @@ int G_snprintf(char *str, size_t size, const char *fmt, ...)
     va_end(ap);
 
     /* Windows' vsnprintf() doesn't always NUL-terminate the buffer */
-    if (count == size)
+    if (count >= 0 && (unsigned int)count == size)
         str[--count] = '\0';
 
     return count;

lib/gis/user_config.c

@@ -30,6 +30,8 @@
 #include <assert.h>
 #include <unistd.h>
 #include <string.h>
+#include <stdint.h>
+#include <stddef.h>
 #ifndef __MINGW32__
 #include <pwd.h>
 #endif
@@ -155,10 +157,11 @@ static int _elem_count_split(char *elems)
     /* Some basic assertions */
     assert(elems != NULL);
     assert((len = strlen(elems)) > 0);
+    assert(len < PTRDIFF_MAX);
     assert(*elems != '/');
 
     begin = elems;
-    for (i = 0; begin != NULL && len > begin - elems; i++) {
+    for (i = 0; begin != NULL && (ptrdiff_t)len > begin - elems; i++) {
         /* check '.' condition */
         if (*begin == '.')
             return 0;