Introduce strnlen() and use it for some string width calculations

Action.c

@@ -402,19 +402,28 @@ static Htop_Reaction actionPrevScreen(State* st) {
 
 Htop_Reaction Action_setScreenTab(State* st, int x) {
    Settings* settings = st->host->settings;
-   int s = SCREEN_TAB_MARGIN_LEFT;
+   const int bracketWidth = (int)strlen("[]");
+
+   if (x < SCREEN_TAB_MARGIN_LEFT) {
+      return 0;
+   }
+
+   int rem = x - SCREEN_TAB_MARGIN_LEFT;
    for (unsigned int i = 0; i < settings->nScreens; i++) {
-      if (x < s) {
-         return 0;
-      }
       const char* tab = settings->screens[i]->heading;
-      int len = strlen(tab);
-      if (x < s + len + 2) {
+      int width = rem >= bracketWidth ? (int)strnlen(tab, rem - bracketWidth + 1) : 0;
+      if (width >= rem - bracketWidth + 1) {
          settings->ssIndex = i;
          setActiveScreen(settings, st, i);
          return HTOP_UPDATE_PANELHDR | HTOP_REFRESH | HTOP_REDRAW_BAR;
       }
-      s += len + 2 + SCREEN_TAB_COLUMN_GAP;
+
+      rem -= bracketWidth + width;
+      if (rem < SCREEN_TAB_COLUMN_GAP) {
+         return 0;
+      }
+
+      rem -= SCREEN_TAB_COLUMN_GAP;
    }
    return 0;
 }

AffinityPanel.c

@@ -10,6 +10,7 @@ in the source distribution for its full text.
 #include "AffinityPanel.h"
 
 #include <assert.h>
+#include <limits.h> // IWYU pragma: keep
 #include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
@@ -321,7 +322,9 @@ static MaskItem* AffinityPanel_addObject(AffinityPanel* this, hwloc_obj_t obj, u
    }
 
    /* "[x] " + "|- " * depth + ("- ")?(if root node) + name */
-   unsigned width = 4 + 3 * depth + (2 * !depth) + strlen(buf);
+   unsigned int indent_width = 4 + 3 * depth + (2 * !depth);
+   assert(sizeof(buf) <= INT_MAX - indent_width);
+   unsigned int width = indent_width + (unsigned int)strlen(buf);
    if (width > this->width) {
       this->width = width;
    }

Meter.c

@@ -54,18 +54,18 @@ static void TextMeterMode_draw(Meter* this, int x, int y, int w) {
    assert(w <= INT_MAX - x);
 
    const char* caption = Meter_getCaption(this);
-   if (w >= 1) {
+   if (w > 0) {
       attrset(CRT_colors[METER_TEXT]);
       mvaddnstr(y, x, caption, w);
    }
    attrset(CRT_colors[RESET_COLOR]);
 
-   int captionLen = strlen(caption);
-   w -= captionLen;
-   if (w < 1) {
+   int captionWidth = w > 0 ? (int)strnlen(caption, w) : 0;
+   if (w <= captionWidth) {
       return;
    }
-   x += captionLen;
+   w -= captionWidth;
+   x += captionWidth;
 
    RichString_begin(out);
    Meter_displayBuffer(this, &out);
@@ -336,15 +336,15 @@ static void LEDMeterMode_draw(Meter* this, int x, int y, int w) {
    attrset(CRT_colors[LED_COLOR]);
 
    const char* caption = Meter_getCaption(this);
-   if (w >= 1) {
+   if (w > 0) {
       mvaddnstr(yText, x, caption, w);
    }
 
-   int captionLen = strlen(caption);
-   if (w <= captionLen) {
+   int captionWidth = w > 0 ? (int)strnlen(caption, w) : 0;
+   if (w <= captionWidth) {
       goto end;
    }
-   int xx = x + captionLen;
+   int xx = x + captionWidth;
 
 #ifdef HAVE_LIBNCURSESW
    if (CRT_utf8)

Row.c

@@ -177,15 +177,15 @@ const char* RowField_alignedTitle(const Settings* settings, RowField field) {
 }
 
 RowField RowField_keyAt(const Settings* settings, int at) {
-   const RowField* fields = (const RowField*) settings->ss->fields;
+   const RowField* fields = settings->ss->fields;
    RowField field;
-   int x = 0;
+   int rem = at;
    for (int i = 0; (field = fields[i]); i++) {
-      int len = strlen(RowField_alignedTitle(settings, field));
-      if (at >= x && at <= x + len) {
+      int len = rem > 0 ? (int)strnlen(RowField_alignedTitle(settings, field), rem) : 0;
+      if (rem <= len) {
          return field;
       }
-      x += len;
+      rem -= len;
    }
    return COMM;
 }

ScreenManager.c

@@ -161,16 +161,18 @@ static void checkRecalculation(ScreenManager* this, double* oldTime, int* sortTi
 }
 
 static inline bool drawTab(const int* y, int* x, int l, const char* name, bool cur) {
+   assert(*x >= 0);
+   assert(*x < l);
+
    attrset(CRT_colors[cur ? SCREENS_CUR_BORDER : SCREENS_OTH_BORDER]);
    mvaddch(*y, *x, '[');
    (*x)++;
    if (*x >= l)
       return false;
-   int nameLen = strlen(name);
-   int n = MINIMUM(l - *x, nameLen);
+   int nameWidth = (int)strnlen(name, l - *x);
    attrset(CRT_colors[cur ? SCREENS_CUR_TEXT : SCREENS_OTH_TEXT]);
-   mvaddnstr(*y, *x, name, n);
-   *x += n;
+   mvaddnstr(*y, *x, name, nameWidth);
+   *x += nameWidth;
    if (*x >= l)
       return false;
    attrset(CRT_colors[cur ? SCREENS_CUR_BORDER : SCREENS_OTH_BORDER]);
@@ -190,9 +192,12 @@ static void ScreenManager_drawScreenTabs(ScreenManager* this) {
    int y = panel->y - 1;
    int x = SCREEN_TAB_MARGIN_LEFT;
 
+   if (x >= l)
+      goto end;
+
    if (this->name) {
       drawTab(&y, &x, l, this->name, true);
-      return;
+      goto end;
    }
 
    for (int s = 0; screens[s]; s++) {
@@ -201,6 +206,8 @@ static void ScreenManager_drawScreenTabs(ScreenManager* this) {
          break;
       }
    }
+
+end:
    attrset(CRT_colors[RESET_COLOR]);
 }
 

XUtils.c

@@ -224,6 +224,17 @@ size_t String_safeStrncpy(char* restrict dest, const char* restrict src, size_t
    return i;
 }
 
+#ifndef HAVE_STRNLEN
+size_t strnlen(const char* str, size_t maxLen) {
+   for (size_t len = 0; len < maxLen; len++) {
+      if (!str[len]) {
+         return len;
+      }
+   }
+   return maxLen;
+}
+#endif
+
 int xAsprintf(char** strp, const char* fmt, ...) {
    va_list vl;
    va_start(vl, fmt);

XUtils.h

@@ -102,6 +102,10 @@ static inline char* String_strchrnul(const char* s, int c) {
 ATTR_NONNULL ATTR_ACCESS3_W(1, 3) ATTR_ACCESS3_R(2, 3)
 size_t String_safeStrncpy(char* restrict dest, const char* restrict src, size_t size);
 
+#ifndef HAVE_STRNLEN
+size_t strnlen(const char* str, size_t maxLen);
+#endif
+
 ATTR_FORMAT(printf, 2, 3) ATTR_NONNULL_N(1, 2)
 int xAsprintf(char** strp, const char* fmt, ...);
 

configure.ac

@@ -372,6 +372,7 @@ AC_CHECK_FUNCS([ \
     readlinkat \
     sched_getscheduler \
     sched_setscheduler \
+    strnlen \
    ])
 
 # strchrnul is available in macOS since 15.4, but the user may specify an older