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INTERNAL: Refactor textual_value_fetch logic #390

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INTERNAL: Refactor textual_value_fetch logic #390

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139 changes: 58 additions & 81 deletions libmemcached/response.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -54,94 +54,79 @@
#include <libmemcached/common.h>
#include <libmemcached/string.hpp>

static size_t tokenize(char *buffer, size_t length, char **tokens, size_t max_tokens)
{
if (buffer[length - 2] != '\r' || buffer[length - 1] != '\n')
return 0;
memset(buffer + length - 2, 0, 2);

char *saveptr;
char *token= strtok_r(buffer, " ", &saveptr);
size_t ntoken= 0;
while (token != NULL)
{
if (ntoken >= max_tokens) return max_tokens + 1;
tokens[ntoken++]= token;
token= strtok_r(NULL, " ", &saveptr);
}
return ntoken;
}

static bool safe_strtoui(char *str, void *out, uintmax_t max_num)
{
/* string to unsinged integer */
errno= 0;
char *endptr;
*(uintmax_t *)out= 0;
uintmax_t num= strtoull(str, &endptr, 10);
if (errno == ERANGE || *endptr != '\0' || num > max_num)
return false;
*(uintmax_t *)out= num;
return true;
}

static memcached_return_t textual_value_fetch(memcached_server_write_instance_st ptr,
char *buffer, size_t buffer_length,
memcached_result_st *result)
{
char *string_ptr;
char *end_ptr;
char *next_ptr;
size_t value_length;
size_t to_read;
ssize_t read_length= 0;
ssize_t value_length;
ssize_t read_length;

if (ptr->root->flags.use_udp)
return memcached_set_error(*ptr, MEMCACHED_NOT_SUPPORTED, MEMCACHED_AT);

WATCHPOINT_ASSERT(ptr->root);
end_ptr= buffer + buffer_length;

memcached_result_reset(result);

string_ptr= buffer;
string_ptr+= 6; /* "VALUE " */
string_ptr= buffer + 6; /* "VALUE " */

char *tokens[4]= {NULL, };
size_t ntoken= tokenize(string_ptr, buffer_length - 6, tokens, 4);
if (ntoken < 3 || ntoken > 4)
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@jhpark816 jhpark816 Oct 2, 2025

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tokens λ°°μ—΄μ˜ 크기λ₯Ό 4둜 μ•Œλ €μ€˜μ„œ tokenize ν•œ κ²ƒμ΄λ―€λ‘œ, λ¦¬ν„΄λ˜λŠ” ntokensλŠ” 4보닀 클 μˆ˜κ°€ 없을 것 κ°™μŠ΅λ‹ˆλ‹€.
if (ntoken < 3) 쑰건만 μ‚¬μš©ν•΄λ„ λ˜μ§€λ§Œ, μ΄λŒ€λ‘œ λ‘λŠ” κ²ƒμœΌλ‘œ ν•˜μ£ .

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@ing-eoking ing-eoking Oct 2, 2025 •
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λ§Œμ•½ partial read둜 μΈν•œ 경우 max_tokdn + 1을 λ°˜ν™˜ν•˜λ„λ‘ ν•˜κ³  μžˆμŠ΅λ‹ˆλ‹€. 였히렀 ntoken > 4 κ°€ 더 μ•Œλ§žμ€ 쑰건이라고 λ³΄μ‹œλ©΄ λ©λ‹ˆλ‹€.

return MEMCACHED_PARTIAL_READ;

/* We load the key */
{
char *key= result->item_key;
size_t key_length= 0;

string_ptr += memcached_array_size(ptr->root->_namespace); /* prefix length */

while (!iscntrl(*string_ptr) && !isspace(*string_ptr)) {
if (key_length < MEMCACHED_MAX_KEY) {
key[key_length]= *string_ptr;
}
key_length++;
string_ptr++;
}

if (key_length < MEMCACHED_MAX_KEY) {
key[key_length]= 0;
result->key_length= key_length;
} else {
snprintf(key + MEMCACHED_MAX_KEY - 4, 4, "...");
result->key_length= MEMCACHED_MAX_KEY - 1;
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@jhpark816 jhpark816 Oct 9, 2025 •
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ν‚€ λ¬Έμžμ—΄μ„ μ½μ–΄λ‚΄λŠ” 뢀뢄은 κΈ°μ‘΄ μ½”λ“œλ₯Ό κ·ΈλŒ€λ‘œ μœ μ§€ν•©μ‹œλ‹€.
ν‚€ λ¬Έμžμ—΄μ˜ tokenize와 μˆ«μžν˜• λ¬Έμžμ—΄μ˜ tokenize 방식이 λ‹€λ₯΄κ³ ,
ν‚€ λ¬Έμžμ—΄μ˜ tokenizeν•˜λŠ” κΈ°μ‘΄ μ½”λ“œκ°€ μΆ©λΆ„νžˆ μ΄ν•΄ν•˜κΈ° 쉽기 λ•Œλ¬Έμž…λ‹ˆλ‹€.

char *key= tokens[0] + memcached_array_size(ptr->root->_namespace);
int key_length= snprintf(result->item_key, MEMCACHED_MAX_KEY, "%s", key);
if (key_length >= MEMCACHED_MAX_KEY)
{
snprintf(result->item_key + MEMCACHED_MAX_KEY - 4, 4, "...");
key_length= MEMCACHED_MAX_KEY - 1;
memcached_set_error(*ptr, MEMCACHED_KEY_TOO_BIG, MEMCACHED_AT);
}
result->key_length= (size_t)key_length;
}

if (end_ptr == string_ptr)
goto read_error;

/* Flags fetch move past space */
string_ptr++;
if (end_ptr == string_ptr)
goto read_error;

for (next_ptr= string_ptr; isdigit(*string_ptr); string_ptr++) {};
result->item_flags= (uint32_t) strtoul(next_ptr, &string_ptr, 10);
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μˆ«μžν˜•μ˜ λ¬Έμžμ—΄λ§Œμ„ ν† ν°ν™”ν•˜λ„λ‘ ν•©μ‹œλ‹€.
기쑴처럼 isdigit() ν•¨μˆ˜λ₯Ό μ΄μš©ν•˜μ—¬ tokenize ν•œλ‹€λ©΄, strtoul() 후에 validation checkλŠ” 없어도 λ©λ‹ˆλ‹€.

int tokenize_numbers(char *buffer, size_t length, char **tokens, size_t max_tokens)

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@ing-eoking ing-eoking Oct 10, 2025

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토큰화 방식을 ν™œμš©ν•΄ λ¦¬νŒ©ν† λ§μ„ μ§„ν–‰ν•˜λŠ” 경우, κ²°κ³Όμ—μ„œ key λΆ€λΆ„λ§Œ λ”°λ‘œ νŒŒμ‹±ν•˜κ³  λ‚˜λ¨Έμ§€ 뢀뢄은 ν† ν°ν™”ν•˜μ—¬ μ²˜λ¦¬ν•˜λŠ” 방식은 κ°œμΈμ μœΌλ‘œλŠ” λ‹€μ†Œ λΆ€μžμ—°μŠ€λŸ½κ²Œ λŠκ»΄μ§‘λ‹ˆλ‹€.

java-client의 κ΅¬ν˜„ 방식을 μ‚΄νŽ΄λ³Έ κ²°κ³Ό, 전체 κ²°κ³Όλ₯Ό λͺ¨λ‘ ν† ν°ν™”ν•œ λ’€ νŒŒμ‹±ν•˜λŠ” 방식을 μ‚¬μš©ν•˜κ³  μžˆμ—ˆμŠ΅λ‹ˆλ‹€.


if (end_ptr == string_ptr)
goto read_error;

/* Length fetch move past space*/
string_ptr++;
if (end_ptr == string_ptr)
goto read_error;

for (next_ptr= string_ptr; isdigit(*string_ptr); string_ptr++) {};
value_length= (size_t)strtoull(next_ptr, &string_ptr, 10);

if (end_ptr == string_ptr)
goto read_error;

/* Skip spaces */
if (*string_ptr == '\r')
if (!safe_strtoui(tokens[1], (void *)&result->item_flags, UINT32_MAX) ||
!safe_strtoui(tokens[2], (void *)&value_length, SSIZE_MAX) ||
(ntoken == 4 && !safe_strtoui(tokens[3], (void *)&result->item_cas, ULLONG_MAX)))
{
/* Skip past the \r\n */
string_ptr+= 2;
}
else
{
string_ptr++;
for (next_ptr= string_ptr; isdigit(*string_ptr); string_ptr++) {};
result->item_cas= strtoull(next_ptr, &string_ptr, 10);
return MEMCACHED_PROTOCOL_ERROR;
}

if (end_ptr < string_ptr)
goto read_error;

/* We add two bytes so that we can walk the \r\n */
if (memcached_failed(memcached_string_check(&result->value, value_length +2)))
{
Expand All @@ -157,7 +142,7 @@ static memcached_return_t textual_value_fetch(memcached_server_write_instance_st
We are null terminating through, which will most likely make
some people lazy about using the return length.
*/
to_read= (value_length) + 2;
size_t to_read= (value_length) + 2;
memcached_return_t rrc= memcached_io_read(ptr, value_ptr, to_read, &read_length);
if (memcached_failed(rrc))
{
Expand All @@ -167,26 +152,18 @@ static memcached_return_t textual_value_fetch(memcached_server_write_instance_st
}
return rrc;
}
}

if (read_length != (ssize_t)(value_length + 2))
{
goto read_error;
}
if (read_length != value_length + 2)
{
return MEMCACHED_PARTIAL_READ;
}

/* This next bit blows the API, but this is internal....*/
{
char *char_ptr;
char_ptr= memcached_string_value_mutable(&result->value);;
char_ptr[value_length]= 0;
char_ptr[value_length +1]= 0;
/* Replace the last "\r\n" characters with '\0' */
memset(value_ptr + value_length, 0, 2);
memcached_string_set_length(&result->value, value_length);
}

return MEMCACHED_SUCCESS;

read_error:
return MEMCACHED_PARTIAL_READ;
}

static memcached_return_t textual_version_fetch(memcached_server_write_instance_st instance, char *buffer)
Expand Down Expand Up @@ -359,7 +336,7 @@ static memcached_return_t textual_read_one_response(memcached_server_write_insta
{
/* We add back in one because we will need to search for END */
memcached_server_response_increment(ptr);
return textual_value_fetch(ptr, buffer, buffer_length, result);
return textual_value_fetch(ptr, buffer, total_read, result);
}
else if (memcmp(buffer, "VERSION", 7) == 0)
{
Expand Down