Gdb print variable in binary trading
If arg is an expression see Expressions , it is not actually evaluated, and any side-effecting operations such as assignments or function calls inside it do not take place. If arg is a variable or an expression, whatis prints its literal type as it is used in the source code. If the type was defined using a typedef , whatis will not print the data type underlying the typedef. If the type of the variable or the expression is a compound data type, such as struct or class , whatis never prints their fields or methods.
If you want to see the members of such a compound data type, use ptype. If arg is a type name that was defined using typedef , whatis unrolls only one level of that typedef. Unrolling means that whatis will show the underlying type used in the typedef declaration of arg. However, if that underlying type is also a typedef , whatis will not unroll it.
Print methods defined in the class. This is the default, but the flag exists in case you change the default with set print type methods. Do not print typedefs defined in the class. Print typedefs defined in the class. This is the default, but the flag exists in case you change the default with set print type typedefs. Print the offsets and sizes of fields in a struct, similar to what the pahole tool does.
Notice the format of the first column of comments. Another interesting line is the marker of a hole in the struct, indicating that it may be possible to pack the struct and make it use less space by reorganizing its fields. In this case, since struct tuv and struct xyz occupy the same space because we are dealing with an union , the offset is not printed for them.
Note how the offset information is now extended to also include how many bits are left to be used in each bitfield. Contrary to whatis , ptype always unrolls any typedef s in its argument declaration, whether the argument is a variable, expression, or a data type. This means that ptype of a variable or an expression will not print literally its type as present in the source code—use whatis for that.
Only typedef s of fields, methods and inner class typedef s of struct s, class es and union s are not unrolled even with ptype. Sometimes, programs use opaque data types or incomplete specifications of complex data structure. For example, given these declarations:. This most often happens when the program or library where the variable is defined includes no debug information at all.
Inspecting the type of a global variable for which GDB has no type information shows:. See no debug info variables , for how to print the values of such variables. Print a brief description of all types whose names match the regular expression regexp or all types in your program, if you supply no argument. This command differs from ptype in two ways: When using ptype or whatis , these printers are consulted when the name of a type is needed.
List all the variables local to a particular scope. See Specify Location , for details about supported forms of location. This command is especially useful for determining what data to collect during a trace experiment , see collect. Show information about the current source file—that is, the source file for the function containing the current point of execution:. Print the names of all source files in your program for which there is debugging information, organized into two lists: Print the names and data types of all defined functions whose names contain a match for regular expression regexp.
Print the names and data types of all variables that are defined outside of functions i. Print the names and data types of all variables except for local variables whose names contain a match for regular expression regexp. Display all Objective-C classes in your program, or with the regexp argument all those matching a particular regular expression. Display all Objective-C selectors in your program, or with the regexp argument all those matching a particular regular expression.
Tell GDB to resolve opaque types. The default is on. A change in the setting of this subcommand will not take effect until the next time symbols for a file are loaded. Tell GDB not to resolve opaque types.
In this case, the type is printed as follows:. The set print symbol-loading command allows you to control the printing of messages when GDB loads symbol information. By default a message is printed for the executable and one for each shared library, and normally this is what you want. However, when debugging apps with large numbers of shared libraries these messages can be annoying.
When set to brief a message is printed for each executable, and when GDB loads a collection of shared libraries at once it will only print one message regardless of the number of shared libraries. When set to off no messages are printed. Show whether messages will be printed when a GDB command entered from the keyboard causes symbol information to be loaded. Write a dump of debugging symbol data into the file filename or the terminal if filename is unspecified.
If -objfile objfile is specified, only dump symbols for that objfile. If -pc address is specified, only dump symbols for the file with code at that address. Note that address may be a symbol like main.
If -source source is specified, only dump symbols for that source file. These commands are used to debug the GDB symbol-reading code. You can use the command info sources to find out which files these are. If regexp is not given, list them all. The output includes expressions which you can copy into a GDB debugging this one to examine a particular structure in more detail.
If we set a breakpoint on a function, that will cause GDB to read the symtab for the compilation unit containing that function:. List the struct linetable from all struct symtab instances whose name matches regexp. If regexp is not given, list the struct linetable from all struct symtab. Set the size of the symbol cache to size.
The default size is intended to be good enough for debugging most applications. This option exists to allow for experimenting with different sizes.
Flush the contents of the symbol cache, all entries are removed. This command is useful when debugging the symbol cache. It is also useful when collecting performance data. Symbol linebuffer is in static storage at address 0xa18, length 4.
Symbol linelength is in static storage at address 0xa1c, length 4. The default value is the empty string. If it is necessary to specify more than one disassembler option, then multiple options can be placed together into a comma separated list. Currently this command is only defined for the Intel x86 family. You can set instruction-set to either intel or att.
Control whether or not GDB will disassemble the next source line or instruction when execution stops. If ON, GDB will display disassembly of the next source line when execution of the program being debugged stops. This is in addition to displaying the source line itself, which GDB always does if possible. If the next source line cannot be displayed for some reason e. This setting causes GDB to display some feedback when you step through a function with no line info or whose source file is unavailable.