Fix strtol(3) quality.
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228bf52b49
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513c5f242d
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@ -1,6 +1,6 @@
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/*******************************************************************************
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/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2011, 2013.
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Copyright(C) Jonas 'Sortie' Termansen 2011, 2013, 2014.
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This file is part of the Sortix C Library.
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This file is part of the Sortix C Library.
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@ -73,6 +73,10 @@ static bool would_multiplication_overflow(T_INT a, T_INT b)
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if ( !a || !b )
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if ( !a || !b )
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return false;
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return false;
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// Trivial cases.
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if ( a == 1 || b == 1 )
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return false;
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// Check if we have a 64-bit integer that it is large enough.
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// Check if we have a 64-bit integer that it is large enough.
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if ( sizeof(T_INT)*2 <= sizeof(int64_t) )
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if ( sizeof(T_INT)*2 <= sizeof(int64_t) )
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{
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{
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@ -111,7 +115,7 @@ static bool would_multiplication_overflow(T_INT a, T_INT b)
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T_UNSIGNED_INT b_abs = b < 0 ? - (T_UNSIGNED_INT) b : b;
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T_UNSIGNED_INT b_abs = b < 0 ? - (T_UNSIGNED_INT) b : b;
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T_UNSIGNED_INT min_abs = - (T_UNSIGNED_INT) T_INT_MIN;
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T_UNSIGNED_INT min_abs = - (T_UNSIGNED_INT) T_INT_MIN;
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T_UNSIGNED_INT max_abs = T_INT_MAX;
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T_UNSIGNED_INT max_abs = T_INT_MAX;
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T_UNSIGNED_INT limit_pos = (0 <= a && 0 <= b) || ( a < 0 && b < 0 );
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T_UNSIGNED_INT limit_pos = (0 <= a && 0 <= b) || (a < 0 && b < 0);
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T_UNSIGNED_INT limit = limit_pos ? max_abs : min_abs;
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T_UNSIGNED_INT limit = limit_pos ? max_abs : min_abs;
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T_UNSIGNED_INT max_b = a_abs / limit;
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T_UNSIGNED_INT max_b = a_abs / limit;
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return max_b < b_abs;
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return max_b < b_abs;
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@ -120,24 +124,23 @@ static bool would_multiplication_overflow(T_INT a, T_INT b)
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extern "C"
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extern "C"
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STRTOL_INT STRTOL(const STRTOL_CHAR* restrict str,
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STRTOL_INT STRTOL(const STRTOL_CHAR* restrict str,
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STRTOL_CHAR** restrict endptr,
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STRTOL_CHAR** restrict end_ptr,
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int base)
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int base)
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{
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{
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const STRTOL_CHAR* origstr = str;
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// Reject bad bases.
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int origbase = base;
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if ( base < 0 || base == 1 || 36 < base )
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{
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if ( end_ptr )
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*end_ptr = (STRTOL_CHAR*) str;
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return errno = EINVAL, 0;
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}
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const STRTOL_CHAR* original_str = str;
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// Skip any leading white space.
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// Skip any leading white space.
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while ( STRTOL_ISSPACE(*str) )
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while ( STRTOL_ISSPACE(*str) )
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str++;
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str++;
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// Reject bad bases.
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if ( base < 0 || 36 < base )
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{
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if ( endptr )
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*endptr = (STRTOL_CHAR*) str;
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return errno = EINVAL, 0;
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}
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bool negative = false;
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bool negative = false;
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STRTOL_CHAR c = *str;
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STRTOL_CHAR c = *str;
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@ -147,43 +150,52 @@ STRTOL_INT STRTOL(const STRTOL_CHAR* restrict str,
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else if ( c == STRTOL_L('+') )
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else if ( c == STRTOL_L('+') )
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str++, negative = false;
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str++, negative = false;
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// Autodetect base 8 or base 16.
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bool actually_negative = !STRTOL_INT_IS_UNSIGNED && negative;
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if ( !base && str[0] == STRTOL_L('0') )
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// Autodetect base if requested.
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if ( base == 0 )
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{
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{
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if ( (str[1] == STRTOL_L('x') || str[1] == STRTOL_L('X')) &&
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if ( str[0] == STRTOL_L('0') &&
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(str[2] && debase(str[2]) < 16) )
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(str[1] == STRTOL_L('x') || str[1] == STRTOL_L('X')) &&
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(0 <= debase(str[2]) && debase(str[2]) < 16) )
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str += 2, base = 16;
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str += 2, base = 16;
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else if ( 0 <= debase(str[1]) )
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else if ( str[0] == STRTOL_L('0') &&
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0 <= debase(str[1]) && debase(str[1]) < 8 )
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str++, base = 8;
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str++, base = 8;
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else
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base = 10;
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}
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}
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// Default to base 10.
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if ( !base )
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base = 10;
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// Skip the leading '0x' prefix in base 16 for hexadecimal integers.
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// Skip the leading '0x' prefix in base 16 for hexadecimal integers.
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if ( origbase == 16 &&
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else if ( base == 16 )
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str[0] == STRTOL_L('0') &&
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{
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(str[1] == STRTOL_L('x') || str[1] == STRTOL_L('X')) &&
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if ( str[0] == STRTOL_L('0') &&
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(0 <= debase(str[2]) && debase(str[2]) < 16) )
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(str[1] == STRTOL_L('x') || str[1] == STRTOL_L('X')) &&
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str += 2;
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(0 <= debase(str[2]) && debase(str[2]) < 16) )
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str += 2;
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}
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// Determine what value will be returned on overflow/underflow.
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// Determine what value will be returned on overflow/underflow.
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STRTOL_INT overflow_value = negative && !STRTOL_INT_IS_UNSIGNED ?
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STRTOL_INT overflow_value =
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STRTOL_INT_MIN :
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actually_negative ? STRTOL_INT_MIN : STRTOL_INT_MAX;
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STRTOL_INT_MAX;
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// Convert a single character at a time.
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// Convert a single character at a time.
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STRTOL_INT result = 0;
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STRTOL_INT result = 0;
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size_t numconvertedchars = 0;
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size_t num_converted_chars = 0;
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bool overflow_occured = false;
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bool overflow_occured = false;
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while ( (c = *str ) )
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while ( (c = *str ) )
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{
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{
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// Stop if we encounterd a character that doesn't fit in this base.
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// Stop if we encounter a character that doesn't fit in this base.
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int val = debase(c);
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int val = debase(c);
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if ( val < 0 || base <= val )
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if ( val < 0 || base <= val )
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break;
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break;
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str++;
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num_converted_chars++;
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if ( overflow_occured )
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continue;
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// Attempt to multiply the accumulator with the current base.
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// Attempt to multiply the accumulator with the current base.
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if ( would_multiplication_overflow<STRTOL_INT,
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if ( would_multiplication_overflow<STRTOL_INT,
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STRTOL_INT_IS_UNSIGNED,
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STRTOL_INT_IS_UNSIGNED,
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@ -191,47 +203,72 @@ STRTOL_INT STRTOL(const STRTOL_CHAR* restrict str,
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STRTOL_INT_MIN,
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STRTOL_INT_MIN,
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STRTOL_INT_MAX>
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STRTOL_INT_MAX>
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(result, (STRTOL_INT) base) )
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(result, (STRTOL_INT) base) )
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overflow_occured = true, result = overflow_value;
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{
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overflow_occured = true;
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result = overflow_value;
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errno = ERANGE;
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continue;
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}
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else
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else
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{
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{
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STRTOL_INT new_result = result * (STRTOL_INT) base;
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STRTOL_INT new_result = result * (STRTOL_INT) base;
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assert( negative || result <= new_result);
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assert( actually_negative || result <= new_result);
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assert(!negative || result >= new_result);
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assert(!actually_negative || result >= new_result);
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result = new_result;
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result = new_result;
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}
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}
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// Nothing needs to be added if we are encountered a zero digit.
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if ( val == 0 )
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{
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}
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// Attempt to add the latest digit to the accumulator (positive).
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// Attempt to add the latest digit to the accumulator (positive).
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if ( (STRTOL_INT_IS_UNSIGNED || !negative) &&
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else if ( !actually_negative &&
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(STRTOL_INT) val <= (STRTOL_INT) (STRTOL_INT_MAX - result) )
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(STRTOL_INT) val <= (STRTOL_INT) (STRTOL_INT_MAX - result) )
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{
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result += (STRTOL_INT) val;
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result += (STRTOL_INT) val;
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}
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// Attempt to subtract the latest digit to the accumulator (negative).
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// Attempt to subtract the latest digit to the accumulator (negative).
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else if ( (!STRTOL_INT_IS_UNSIGNED && negative) &&
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else if ( actually_negative &&
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(STRTOL_UNSIGNED_INT) val < ((STRTOL_UNSIGNED_INT) result - (STRTOL_UNSIGNED_INT) STRTOL_INT_MIN) )
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(STRTOL_UNSIGNED_INT) val <
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((STRTOL_UNSIGNED_INT) result -
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(STRTOL_UNSIGNED_INT) STRTOL_INT_MIN) )
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{
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result -= (STRTOL_INT) val;
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result -= (STRTOL_INT) val;
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}
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// Handle the case where the addition/subtract would overflow/underflow.
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// Otherwise, the addition/subtract would overflow/underflow.
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else
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else
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overflow_occured = true, result = overflow_value;
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{
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overflow_occured = true;
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str++;
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result = overflow_value;
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numconvertedchars++;
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errno = ERANGE;
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continue;
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}
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}
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}
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// If no characters were successfully converted, rewind to the start, also
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// If no characters were successfully converted, rewind to the start.
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// rewinding past skipped whitespace and sign characters and such.
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if ( !num_converted_chars )
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if ( !numconvertedchars )
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{
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str = origstr, result = 0;
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errno = EINVAL;
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str = original_str;
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}
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// Let the caller know where we got to.
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// Let the caller know where we got to.
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if ( endptr )
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if ( end_ptr )
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*endptr = (STRTOL_CHAR*) str;
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*end_ptr = (STRTOL_CHAR*) str;
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// Handle the special case where we are creating an unsigned integer and the
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// Handle the special case where we are creating an unsigned integer and the
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// string was negative and non-zero and no overflow occured, then we treat
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// string was negative. The result is the negation assuming no overflow.
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// it as (the maximum value+1) minus (the negative string as integer).
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if ( STRTOL_INT_IS_UNSIGNED && negative )
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if ( STRTOL_INT_IS_UNSIGNED && negative && result && !overflow_occured )
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{
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result = STRTOL_INT_MAX - (result-1);
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if ( overflow_occured )
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result = STRTOL_INT_MAX;
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else
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result = -result;
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}
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return result;
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return result;
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}
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}
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