SystemTap: string.c Source File

00001 #ifndef _STRING_C_ /* -*- linux-c -*- */
-00002 #define _STRING_C_
-00003 
-00004 #include <linux/config.h>
-00005 
-00006 /** @file string.c
-00007  * @brief Implements String type.
-00008  */
-00009 /** @addtogroup string String Functions
-00010  *
-00011  * One of the biggest restrictions the library has is that it cannot allocate things like strings off the stack.
-00012  * It is also not a good idea to dynamically allocate space for strings with kmalloc().  That leaves us with 
-00013  * statically allocated space for strings. This is what is implemented in the String module.  Strings use
-00014  * preallocated per-cpu buffers and are safe to use (unlike C strings).
-00015  * @{
-00016  */
-00017 
-00018 /** Maximum string size allowed in Strings */
-00019 #ifndef STP_STRING_SIZE
-00020 #define STP_STRING_SIZE 2048
-00021 #endif
-00022 
-00023 struct string {
-00024         short len;
-00025         short global;
-00026         char buf[STP_STRING_SIZE];
-00027 };
-00028 
-00029 static struct string _stp_string[STP_NUM_STRINGS][NR_CPUS];
-00030 
-00031 typedef struct string *String;
-00032 
-00033 /** Initialize a String for our use.
-00034  * This grabs one of the global Strings for our use.
-00035  *
-00036  * @param num Number of the preallocated String to use. 
-00037  * #STP_NUM_STRINGS are statically allocated for our use. The
-00038  * translator (or author) should be sure to grab a free one.
-00039  * @todo Global (and static) Strings not implemented yet. 
-00040  */
-00041 
-00042 String _stp_string_init (int num)
-00043 {
-00044         int global = 0;
-00045         String str;
-00046 
-00047         if (num  < 0) {
-00048                 num = -num;
-00049                 global = 1;
-00050         }
-00051         
-00052         if (num >= STP_NUM_STRINGS) {
-00053                 _stp_log ("_stp_string_init internal error: requested string exceeded allocated number");
-00054                 return NULL;
-00055         }
-00056 
-00057         if (global)
-00058                 str = &_stp_string[num][0];
-00059         else
-00060                 str = &_stp_string[num][smp_processor_id()];
-00061 
-00062         str->global = global;
-00063         str->len = 0;
-00064         return str;
-00065 }
-00066 
-00067 
-00068 /** Sprintf into a String.
-00069  * Like printf, except output goes into a String.
-00070  * Safe because overflowing the buffer is not allowed.
-00071  * Size is limited by length of String, #STP_STRING_SIZE.
-00072  *
-00073  * @param str String
-00074  * @param fmt A printf-style format string followed by a 
-00075  * variable number of args.
-00076  */
-00077 void _stp_sprintf (String str, const char *fmt, ...)
-00078 {
-00079         int num;
-00080         va_list args;
-00081         va_start(args, fmt);
-00082         num = vscnprintf(str->buf + str->len, STP_STRING_SIZE - str->len - 1, fmt, args);
-00083         va_end(args);
-00084         if (num > 0)
-00085                 str->len += num;
-00086 }
-00087 
-00088 /** Vsprintf into a String
-00089  * Use this if your function already has a va_list.
-00090  * You probably want _stp_sprintf().
-00091  */
-00092 void _stp_vsprintf (String str, const char *fmt, va_list args)
-00093 {
-00094         int num;
-00095         num = vscnprintf(str->buf + str->len, STP_STRING_SIZE - str->len - 1, fmt, args);
-00096         if (num > 0)
-00097                 str->len += num;
-00098 }
-00099 
-00100 /** ConCATenate (append) a C string to a String.
-00101  * Like strcat().
-00102  * @param str1 String
-00103  * @param str2 C string (char *)
-00104  * @sa _stp_string_cat
-00105  */
-00106 void _stp_string_cat_cstr (String str1, const char *str2)
-00107 {
-00108         int num = strlen (str2);
-00109         if (num > STP_STRING_SIZE - str1->len - 1)
-00110                 num = STP_STRING_SIZE - str1->len - 1;
-00111         strncpy (str1->buf + str1->len, str2, num+1);
-00112         str1->len += num;
-00113 }
-00114 
-00115 /** ConCATenate (append) a String to a String.
-00116  * Like strcat().
-00117  * @param str1 String
-00118  * @param str2 String
-00119  * @sa _stp_string_cat
-00120  */
-00121 void _stp_string_cat_string (String str1, String str2)
-00122 {
-00123         int num = str2->len;
-00124         if (num > STP_STRING_SIZE - str1->len - 1)
-00125                 num = STP_STRING_SIZE - str1->len - 1;
-00126         strncpy (str1->buf + str1->len, str2->buf, num);
-00127         str1->len += num;
-00128 }
-00129 
-00130 /** Get a pointer to String's buffer
-00131  * For rare cases when a C string is needed and you have a String.
-00132  * One example is when you want to print a String with _stp_printf().
-00133  * @param str String
-00134  * @returns A C string (char *)
-00135  * @note Readonly. Don't write to this pointer or it will mess up
-00136  * the internal String state and probably mess up your output or crash something.
-00137  */
-00138 char * _stp_string_ptr (String str)
-00139 {
-00140         return str->buf;
-00141 }
-00142 
-00143 
-00144 /** ConCATenate (append) a String or C string to a String.
-00145  * This macro selects the proper function to call.
-00146  * @param str1 A String
-00147  * @param str2 A String or C string (char *)
-00148  * @sa _stp_string_cat_cstr _stp_string_cat_string
-00149  */
-00150 #define _stp_string_cat(str1, str2)                                     \
-00151   ({                                                            \
-00152           if (__builtin_types_compatible_p (typeof (str2), char[])) {   \
-00153                   char *x = (char *)str2;                               \
-00154                   _str_string_cat_cstr(str1,x);                         \
-00155           } else {                                                      \
-00156                   String x = (String)str2;                              \
-00157                   _str_string_cat_string(str1,x);                       \
-00158           }                                                             \
-00159   })
-00160 
-00161 /** @} */
-00162 #endif /* _STRING_C_ */
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