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OS-1723 DTrace should speak JSON
Reviewed by: Bryan Cantrill <bmc@joyent.com>

*** 90,99 **** --- 90,100 ---- #include <sys/mkdev.h> #include <sys/kdi.h> #include <sys/zone.h> #include <sys/socket.h> #include <netinet/in.h> + #include "strtolctype.h" /* * DTrace Tunable Variables * * The following variables may be tuned by adding a line to /etc/system that
*** 875,884 **** --- 876,937 ---- return (dtrace_canload((uintptr_t)src, sz, mstate, vstate)); } /* + * Convert a string to a signed integer using safe loads. + * + * NOTE: This function uses various macros from strtolctype.h to manipulate + * digit values, etc -- these have all been checked to ensure they make + * no additional function calls. + */ + static int64_t + dtrace_strtoll(char *input, int base, size_t limit) + { + uintptr_t pos = (uintptr_t)input; + int64_t val = 0; + int x; + boolean_t neg = B_FALSE; + char c, cc, ccc; + uintptr_t end = pos + limit; + + /* + * Consume any whitespace preceding digits. + */ + while ((c = dtrace_load8(pos)) == ' ' || c == '\t') + pos++; + + /* + * Handle an explicit sign if one is present. + */ + if (c == '-' || c == '+') { + if (c == '-') + neg = B_TRUE; + c = dtrace_load8(++pos); + } + + /* + * Check for an explicit hexadecimal prefix ("0x" or "0X") and skip it + * if present. + */ + if (base == 16 && c == '0' && ((cc = dtrace_load8(pos + 1)) == 'x' || + cc == 'X') && isxdigit(ccc = dtrace_load8(pos + 2))) { + pos += 2; + c = ccc; + } + + /* + * Read in contiguous digits until the first non-digit character. + */ + for (; pos < end && c != '\0' && lisalnum(c) && (x = DIGIT(c)) < base; + c = dtrace_load8(++pos)) + val = val * base + x; + + return (neg ? -val : val); + } + + /* * Compare two strings using safe loads. */ static int dtrace_strncmp(char *s1, char *s2, size_t limit) {
*** 3351,3361 **** --- 3404,3871 ---- DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP); return (0); } } + + typedef enum dtrace_json_state { + DTRACE_JSON_REST = 1, + DTRACE_JSON_OBJECT, + DTRACE_JSON_STRING, + DTRACE_JSON_STRING_ESCAPE, + DTRACE_JSON_STRING_ESCAPE_UNICODE, + DTRACE_JSON_COLON, + DTRACE_JSON_COMMA, + DTRACE_JSON_VALUE, + DTRACE_JSON_IDENTIFIER, + DTRACE_JSON_NUMBER, + DTRACE_JSON_NUMBER_FRAC, + DTRACE_JSON_NUMBER_EXP, + DTRACE_JSON_COLLECT_OBJECT + } dtrace_json_state_t; + /* + * This function possesses just enough knowledge about JSON to extract a single + * value from a JSON string and store it in the scratch buffer. It is able + * to extract nested object values, and members of arrays by index. + * + * elemlist is a list of JSON keys, stored as packed NUL-terminated strings, to + * be looked up as we descend into the object tree. e.g. + * + * foo[0].bar.baz[32] --> "foo" NUL "0" NUL "bar" NUL "baz" NUL "32" NUL + * with nelems = 5. + * + * The run time of this function must be bounded above by strsize to limit the + * amount of work done in probe context. As such, it is implemented as a + * simple state machine, reading one character at a time using safe loads + * until we find the requested element, hit a parsing error or run off the + * end of the object or string. + * + * As there is no way for a subroutine to return an error without interrupting + * clause execution, we simply return NULL in the event of a missing key or any + * other error condition. Each NULL return in this function is commented with + * the error condition it represents -- parsing or otherwise. + * + * The set of states for the state machine closely matches the JSON + * specification (http://json.org/). Briefly: + * + * DTRACE_JSON_REST: + * Skip whitespace until we find either a top-level Object, moving + * to DTRACE_JSON_OBJECT; or an Array, moving to DTRACE_JSON_VALUE. + * + * DTRACE_JSON_OBJECT: + * Locate the next key String in an Object. Sets a flag to denote + * the next String as a key string and moves to DTRACE_JSON_STRING. + * + * DTRACE_JSON_COLON: + * Skip whitespace until we find the colon that separates key Strings + * from their values. Once found, move to DTRACE_JSON_VALUE. + * + * DTRACE_JSON_VALUE: + * Detects the type of the next value (String, Number, Identifier, Object + * or Array) and routes to the states that process that type. Here we also + * deal with the element selector list if we are requested to traverse down + * into the object tree. + * + * DTRACE_JSON_COMMA: + * Skip whitespace until we find the comma that separates key-value pairs + * in Objects (returning to DTRACE_JSON_OBJECT) or values in Arrays + * (similarly DTRACE_JSON_VALUE). All following literal value processing + * states return to this state at the end of their value, unless otherwise + * noted. + * + * DTRACE_JSON_NUMBER, DTRACE_JSON_NUMBER_FRAC, DTRACE_JSON_NUMBER_EXP: + * Processes a Number literal from the JSON, including any exponent + * component that may be present. Numbers are returned as strings, which + * may be passed to strtoll() if an integer is required. + * + * DTRACE_JSON_IDENTIFIER: + * Processes a "true", "false" or "null" literal in the JSON. + * + * DTRACE_JSON_STRING, DTRACE_JSON_STRING_ESCAPE, + * DTRACE_JSON_STRING_ESCAPE_UNICODE: + * Processes a String literal from the JSON, whether the String denotes + * a key, a value or part of a larger Object. Handles all escape sequences + * present in the specification, including four-digit unicode characters, + * but merely includes the escape sequence without converting it to the + * actual escaped character. If the String is flagged as a key, we + * move to DTRACE_JSON_COLON rather than DTRACE_JSON_COMMA. + * + * DTRACE_JSON_COLLECT_OBJECT: + * This state collects an entire Object (or Array), correctly handling + * embedded strings. If the full element selector list matches this nested + * object, we return the Object in full as a string. If not, we use this + * state to skip to the next value at this level and continue processing. + * + * NOTE: This function uses various macros from strtolctype.h to manipulate + * digit values, etc -- these have all been checked to ensure they make + * no additional function calls. + */ + static char * + dtrace_json(uint64_t size, uintptr_t json, char *elemlist, int nelems, + char *dest) + { + dtrace_json_state_t state = DTRACE_JSON_REST; + int64_t array_elem = INT64_MIN; + int64_t array_pos = 0; + uint8_t escape_unicount = 0; + boolean_t string_is_key = B_FALSE; + boolean_t collect_object = B_FALSE; + boolean_t found_key = B_FALSE; + boolean_t in_array = B_FALSE; + uint32_t braces = 0, brackets = 0; + char *elem = elemlist; + char *dd = dest; + uintptr_t cur; + + for (cur = json; cur < json + size; cur++) { + char cc = dtrace_load8(cur); + if (cc == '\0') + return (NULL); + + switch (state) { + case DTRACE_JSON_REST: + if (isspace(cc)) + break; + + if (cc == '{') { + state = DTRACE_JSON_OBJECT; + break; + } + + if (cc == '[') { + in_array = B_TRUE; + array_pos = 0; + array_elem = dtrace_strtoll(elem, 10, size); + found_key = array_elem == 0 ? B_TRUE : B_FALSE; + state = DTRACE_JSON_VALUE; + break; + } + + /* + * ERROR: expected to find a top-level object or array. + */ + return (NULL); + case DTRACE_JSON_OBJECT: + if (isspace(cc)) + break; + + if (cc == '"') { + state = DTRACE_JSON_STRING; + string_is_key = B_TRUE; + break; + } + + /* + * ERROR: either the object did not start with a key + * string, or we've run off the end of the object + * without finding the requested key. + */ + return (NULL); + case DTRACE_JSON_STRING: + if (cc == '\\') { + *dd++ = '\\'; + state = DTRACE_JSON_STRING_ESCAPE; + break; + } + + if (cc == '"') { + if (collect_object) { + /* + * We don't reset the dest here, as + * the string is part of a larger + * object being collected. + */ + *dd++ = cc; + collect_object = B_FALSE; + state = DTRACE_JSON_COLLECT_OBJECT; + break; + } + *dd = '\0'; + dd = dest; /* reset string buffer */ + if (string_is_key) { + if (dtrace_strncmp(dest, elem, + size) == 0) + found_key = B_TRUE; + } else if (found_key) { + if (nelems > 1) { + /* + * We expected an object, not + * this string. + */ + return (NULL); + } + return (dest); + } + state = string_is_key ? DTRACE_JSON_COLON : + DTRACE_JSON_COMMA; + string_is_key = B_FALSE; + break; + } + + *dd++ = cc; + break; + case DTRACE_JSON_STRING_ESCAPE: + *dd++ = cc; + if (cc == 'u') { + escape_unicount = 0; + state = DTRACE_JSON_STRING_ESCAPE_UNICODE; + } else { + state = DTRACE_JSON_STRING; + } + break; + case DTRACE_JSON_STRING_ESCAPE_UNICODE: + if (!isxdigit(cc)) { + /* + * ERROR: invalid unicode escape, expected + * four valid hexidecimal digits. + */ + return (NULL); + } + + *dd++ = cc; + if (++escape_unicount == 4) + state = DTRACE_JSON_STRING; + break; + case DTRACE_JSON_COLON: + if (isspace(cc)) + break; + + if (cc == ':') { + state = DTRACE_JSON_VALUE; + break; + } + + /* + * ERROR: expected a colon. + */ + return (NULL); + case DTRACE_JSON_COMMA: + if (isspace(cc)) + break; + + if (cc == ',') { + if (in_array) { + state = DTRACE_JSON_VALUE; + if (++array_pos == array_elem) + found_key = B_TRUE; + } else { + state = DTRACE_JSON_OBJECT; + } + break; + } + + /* + * ERROR: either we hit an unexpected character, or + * we reached the end of the object or array without + * finding the requested key. + */ + return (NULL); + case DTRACE_JSON_IDENTIFIER: + if (islower(cc)) { + *dd++ = cc; + break; + } + + *dd = '\0'; + dd = dest; /* reset string buffer */ + + if (dtrace_strncmp(dest, "true", 5) == 0 || + dtrace_strncmp(dest, "false", 6) == 0 || + dtrace_strncmp(dest, "null", 5) == 0) { + if (found_key) { + if (nelems > 1) { + /* + * ERROR: We expected an object, + * not this identifier. + */ + return (NULL); + } + return (dest); + } else { + cur--; + state = DTRACE_JSON_COMMA; + break; + } + } + + /* + * ERROR: we did not recognise the identifier as one + * of those in the JSON specification. + */ + return (NULL); + case DTRACE_JSON_NUMBER: + if (cc == '.') { + *dd++ = cc; + state = DTRACE_JSON_NUMBER_FRAC; + break; + } + + if (cc == 'x' || cc == 'X') { + /* + * ERROR: specification explicitly excludes + * hexidecimal or octal numbers. + */ + return (NULL); + } + + /* FALLTHRU */ + case DTRACE_JSON_NUMBER_FRAC: + if (cc == 'e' || cc == 'E') { + *dd++ = cc; + state = DTRACE_JSON_NUMBER_EXP; + break; + } + + if (cc == '+' || cc == '-') { + /* + * ERROR: expect sign as part of exponent only. + */ + return (NULL); + } + /* FALLTHRU */ + case DTRACE_JSON_NUMBER_EXP: + if (isdigit(cc) || cc == '+' || cc == '-') { + *dd++ = cc; + break; + } + + *dd = '\0'; + dd = dest; /* reset string buffer */ + if (found_key) { + if (nelems > 1) { + /* + * ERROR: We expected an object, not + * this number. + */ + return (NULL); + } + return (dest); + } + + cur--; + state = DTRACE_JSON_COMMA; + break; + case DTRACE_JSON_VALUE: + if (isspace(cc)) + break; + + if (cc == '{' || cc == '[') { + if (nelems > 1 && found_key) { + in_array = cc == '[' ? B_TRUE : B_FALSE; + /* + * If our element selector directs us + * to descend into this nested object, + * then move to the next selector + * element in the list and restart the + * state machine. + */ + while (*elem != '\0') + elem++; + elem++; /* skip the inter-element NUL */ + nelems--; + dd = dest; + if (in_array) { + state = DTRACE_JSON_VALUE; + array_pos = 0; + array_elem = dtrace_strtoll( + elem, 10, size); + found_key = array_elem == 0 ? + B_TRUE : B_FALSE; + } else { + found_key = B_FALSE; + state = DTRACE_JSON_OBJECT; + } + break; + } + + /* + * Otherwise, we wish to either skip this + * nested object or return it in full. + */ + if (cc == '[') + brackets = 1; + else + braces = 1; + *dd++ = cc; + state = DTRACE_JSON_COLLECT_OBJECT; + break; + } + + if (cc == '"') { + state = DTRACE_JSON_STRING; + break; + } + + if (islower(cc)) { + /* + * Here we deal with true, false and null. + */ + *dd++ = cc; + state = DTRACE_JSON_IDENTIFIER; + break; + } + + if (cc == '-' || isdigit(cc)) { + *dd++ = cc; + state = DTRACE_JSON_NUMBER; + break; + } + + /* + * ERROR: unexpected character at start of value. + */ + return (NULL); + case DTRACE_JSON_COLLECT_OBJECT: + if (cc == '\0') + /* + * ERROR: unexpected end of input. + */ + return (NULL); + + *dd++ = cc; + if (cc == '"') { + collect_object = B_TRUE; + state = DTRACE_JSON_STRING; + break; + } + + if (cc == ']') { + if (brackets-- == 0) { + /* + * ERROR: unbalanced brackets. + */ + return (NULL); + } + } else if (cc == '}') { + if (braces-- == 0) { + /* + * ERROR: unbalanced braces. + */ + return (NULL); + } + } else if (cc == '{') { + braces++; + } else if (cc == '[') { + brackets++; + } + + if (brackets == 0 && braces == 0) { + if (found_key) { + *dd = '\0'; + return (dest); + } + dd = dest; /* reset string buffer */ + state = DTRACE_JSON_COMMA; + } + break; + } + } + return (NULL); + } + + /* * Emulate the execution of DTrace ID subroutines invoked by the call opcode. * Notice that we don't bother validating the proper number of arguments or * their types in the tuple stack. This isn't needed because all argument * interpretation is safe because of our load safety -- the worst that can * happen is that a bogus program can obtain bogus results.
*** 4051,4060 **** --- 4561,4629 ---- mstate->dtms_scratch_ptr += size; regs[rd] = (uintptr_t)d; break; } + case DIF_SUBR_JSON: { + uint64_t size = state->dts_options[DTRACEOPT_STRSIZE]; + uintptr_t json = tupregs[0].dttk_value; + size_t jsonlen = dtrace_strlen((char *)json, size); + uintptr_t elem = tupregs[1].dttk_value; + size_t elemlen = dtrace_strlen((char *)elem, size); + + char *dest = (char *)mstate->dtms_scratch_ptr; + char *elemlist = (char *)mstate->dtms_scratch_ptr + jsonlen + 1; + char *ee = elemlist; + int nelems = 1; + uintptr_t cur; + + if (!dtrace_canload(json, jsonlen + 1, mstate, vstate) || + !dtrace_canload(elem, elemlen + 1, mstate, vstate)) { + regs[rd] = NULL; + break; + } + + if (!DTRACE_INSCRATCH(mstate, jsonlen + 1 + elemlen + 1)) { + DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH); + regs[rd] = NULL; + break; + } + + /* + * Read the element selector and split it up into a packed list + * of strings. + */ + for (cur = elem; cur < elem + elemlen; cur++) { + char cc = dtrace_load8(cur); + + if (cur == elem && cc == '[') { + /* + * If the first element selector key is + * actually an array index then ignore the + * bracket. + */ + continue; + } + + if (cc == ']') + continue; + + if (cc == '.' || cc == '[') { + nelems++; + cc = '\0'; + } + + *ee++ = cc; + } + *ee++ = '\0'; + + if ((regs[rd] = (uintptr_t)dtrace_json(size, json, elemlist, + nelems, dest)) != NULL) + mstate->dtms_scratch_ptr += jsonlen + 1; + break; + } + case DIF_SUBR_TOUPPER: case DIF_SUBR_TOLOWER: { uintptr_t s = tupregs[0].dttk_value; uint64_t size = state->dts_options[DTRACEOPT_STRSIZE]; char *dest = (char *)mstate->dtms_scratch_ptr, c;
*** 4358,4367 **** --- 4927,4958 ---- } break; } + case DIF_SUBR_STRTOLL: { + uintptr_t s = tupregs[0].dttk_value; + uint64_t size = state->dts_options[DTRACEOPT_STRSIZE]; + int base = 10; + + if (nargs > 1) { + if ((base = tupregs[1].dttk_value) <= 1 || + base > ('z' - 'a' + 1) + ('9' - '0' + 1)) { + *flags |= CPU_DTRACE_ILLOP; + break; + } + } + + if (!dtrace_strcanload(s, size, mstate, vstate)) { + regs[rd] = INT64_MIN; + break; + } + + regs[rd] = dtrace_strtoll((char *)s, base, size); + break; + } + case DIF_SUBR_LLTOSTR: { int64_t i = (int64_t)tupregs[0].dttk_value; uint64_t val, digit; uint64_t size = 65; /* enough room for 2^64 in binary */ char *end = (char *)mstate->dtms_scratch_ptr + size - 1;
*** 8887,8897 **** --- 9478,9490 ---- subr == DIF_SUBR_COPYINSTR || subr == DIF_SUBR_INDEX || subr == DIF_SUBR_INET_NTOA || subr == DIF_SUBR_INET_NTOA6 || subr == DIF_SUBR_INET_NTOP || + subr == DIF_SUBR_JSON || subr == DIF_SUBR_LLTOSTR || + subr == DIF_SUBR_STRTOLL || subr == DIF_SUBR_RINDEX || subr == DIF_SUBR_STRCHR || subr == DIF_SUBR_STRJOIN || subr == DIF_SUBR_STRRCHR || subr == DIF_SUBR_STRSTR ||