mirror of https://github.com/xzeldon/htop.git
Process.{h,c}: Use integer types that are more portable
When building on a 32-bit system, the compiler warned that the following line uses a constant whose value is the overflow result of a compile-time computation: Process.c (line 109): } else if (number < 10000 * ONE_M) { Namely, this constant expression: 10000 * ONE_M was intended to produce the following value: 10485760000 However, the result overflowed to produce: 1895825408 The reason for this overflow is as follows: o The macros are expanded: 10000 * (ONE_K * ONE_K) 10000 * (1024L * 1024L) o The untyped constant expression "10000" is typed: 10000U * (1024L * 1024L) o The parenthesized expression is evaluated: 10000U * (1048576L) o The left operand ("10000U") is converted: 10000L * (1048576L) Unbound by integer sizes, that last multiplication would produce the following value: 10485760000 However, on a 32-bit machine, where a long is 32 bits (really 31 bits when talking about positive numbers), the maximum value that can be computed is 2**31-1: 2147483647 Consequently, the computation overflows. o The compiler produces a long int value that is the the result of overflow (10485760000 % 2**31): 1895825408L Actually, I think this overflow is implementation-defined, so it's not even a portable description of what happens. The solution is to use a long long int (or, even better, an unsigned long long int) type for the constant expression; the C standard mandates a sufficiently large maximum value for such types. Hence, the following change is made to the bad line: - } else if (number < 10000 * ONE_M) { + } else if (number < 10000ULL * ONE_M) { However, the whole line is now patently silly, because the variable "number" is typed "unsigned long", and so it will always be less than the constant expression (the compiler will warn about this, too). Hence, "number" must be typed "unsigned long long"; however, this necessitates changing all of the string formats from something like "%lu" to something like "%llu". Et voila! This commit is born. Then, for the sake of completeness, the declared types of the constant-expression macros are updated: o ONE_K is made unsigned (a "UL" instead of "L") o ONE_T is computed by introducing "1ULL *" o Similar changes are made for ONE_DECIMAL_{K,T} Also, a non-portable overflow-conversion to a signed value has been replaced with a portable comparison: - if ((long long) number == -1LL) { + if (number == ULLONG_MAX) { It might be worth reviewing the rest of the code for other cases where overflows are not handled correctly; even at runtime, it's often necessary to check for overflow unless such behavior is expected (especially for signed integer values, for which overflow has implementation-defined behavior).
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parent
241e4b3dbf
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28
Process.c
28
Process.c
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@ -55,7 +55,7 @@ void Process_setupColumnWidths() {
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xSnprintf(Process_pidFormat, sizeof(Process_pidFormat), "%%%dd ", digits);
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}
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void Process_humanNumber(RichString* str, unsigned long number, bool coloring) {
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void Process_humanNumber(RichString* str, unsigned long long number, bool coloring) {
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char buffer[11];
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int len;
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@ -71,48 +71,48 @@ void Process_humanNumber(RichString* str, unsigned long number, bool coloring) {
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if (number < 1000) {
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//Plain number, no markings
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len = snprintf(buffer, 10, "%5lu ", number);
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len = snprintf(buffer, 10, "%5llu ", number);
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RichString_appendn(str, processColor, buffer, len);
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} else if (number < 100000) {
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//2 digit MB, 3 digit KB
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len = snprintf(buffer, 10, "%2lu", number/1000);
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len = snprintf(buffer, 10, "%2llu", number/1000);
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RichString_appendn(str, processMegabytesColor, buffer, len);
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number %= 1000;
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len = snprintf(buffer, 10, "%03lu ", number);
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len = snprintf(buffer, 10, "%03llu ", number);
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RichString_appendn(str, processColor, buffer, len);
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} else if (number < 1000 * ONE_K) {
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//3 digit MB
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number /= ONE_K;
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len = snprintf(buffer, 10, "%4luM ", number);
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len = snprintf(buffer, 10, "%4lluM ", number);
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RichString_appendn(str, processMegabytesColor, buffer, len);
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} else if (number < 10000 * ONE_K) {
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//1 digit GB, 3 digit MB
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number /= ONE_K;
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len = snprintf(buffer, 10, "%1lu", number/1000);
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len = snprintf(buffer, 10, "%1llu", number/1000);
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RichString_appendn(str, processGigabytesColor, buffer, len);
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number %= 1000;
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len = snprintf(buffer, 10, "%03luM ", number);
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len = snprintf(buffer, 10, "%03lluM ", number);
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RichString_appendn(str, processMegabytesColor, buffer, len);
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} else if (number < 100000 * ONE_K) {
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//2 digit GB, 1 digit MB
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number /= 100 * ONE_K;
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len = snprintf(buffer, 10, "%2lu", number/10);
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len = snprintf(buffer, 10, "%2llu", number/10);
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RichString_appendn(str, processGigabytesColor, buffer, len);
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number %= 10;
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len = snprintf(buffer, 10, ".%1luG ", number);
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len = snprintf(buffer, 10, ".%1lluG ", number);
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RichString_appendn(str, processMegabytesColor, buffer, len);
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} else if (number < 1000 * ONE_M) {
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//3 digit GB
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number /= ONE_M;
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len = snprintf(buffer, 10, "%4luG ", number);
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len = snprintf(buffer, 10, "%4lluG ", number);
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RichString_appendn(str, processGigabytesColor, buffer, len);
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} else if (number < 10000 * ONE_M) {
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} else if (number < 10000ULL * ONE_M) {
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//1 digit TB, 3 digit GB
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number /= ONE_M;
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len = snprintf(buffer, 10, "%1lu", number/1000);
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len = snprintf(buffer, 10, "%1llu", number/1000);
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RichString_appendn(str, largeNumberColor, buffer, len);
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number %= 1000;
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len = snprintf(buffer, 10, "%03luG ", number);
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len = snprintf(buffer, 10, "%03lluG ", number);
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RichString_appendn(str, processGigabytesColor, buffer, len);
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} else {
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//2 digit TB and above
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@ -134,7 +134,7 @@ void Process_colorNumber(RichString* str, unsigned long long number, bool colori
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processShadowColor = CRT_colors[PROCESS];
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}
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if ((long long) number == -1LL) {
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if (number == ULLONG_MAX) {
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int len = snprintf(buffer, 13, " no perm ");
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RichString_appendn(str, CRT_colors[PROCESS_SHADOW], buffer, len);
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} else if (number >= 100000LL * ONE_DECIMAL_T) {
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10
Process.h
10
Process.h
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@ -138,19 +138,19 @@ typedef struct ProcessClass_ {
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#define Process_sortState(state) ((state) == 'I' ? 0x100 : (state))
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#define ONE_K 1024L
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#define ONE_K 1024UL
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#define ONE_M (ONE_K * ONE_K)
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#define ONE_G (ONE_M * ONE_K)
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#define ONE_T ((long long)ONE_G * ONE_K)
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#define ONE_T (1ULL * ONE_G * ONE_K)
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#define ONE_DECIMAL_K 1000L
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#define ONE_DECIMAL_K 1000UL
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#define ONE_DECIMAL_M (ONE_DECIMAL_K * ONE_DECIMAL_K)
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#define ONE_DECIMAL_G (ONE_DECIMAL_M * ONE_DECIMAL_K)
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#define ONE_DECIMAL_T ((long long)ONE_DECIMAL_G * ONE_DECIMAL_K)
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#define ONE_DECIMAL_T (1ULL * ONE_DECIMAL_G * ONE_DECIMAL_K)
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void Process_setupColumnWidths(void);
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void Process_humanNumber(RichString* str, unsigned long number, bool coloring);
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void Process_humanNumber(RichString* str, unsigned long long number, bool coloring);
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void Process_colorNumber(RichString* str, unsigned long long number, bool coloring);
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